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Publications of year 2008

Books and proceedings

  1. Ingo Walterscheid. Bistatisches SAR - Signaltheoretische und experimentelle Untersuchung der bistatischen Radarbildgebung, FHR-Schriftenreihe. Shaker Verlag, 2008. Keyword(s): SAR Processing, Bistatic SAR, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Time-Domain Back-Projection, Back-Projection, NuSAR, Airborne SAR, PAMIR, Elektrotechnik Radartechnik Signalverarbeitung Radarsignalverarbeitung.
    @Book{walterscheid2008Diss:BistaticSAR,
    Title = {Bistatisches SAR - Signaltheoretische und experimentelle Untersuchung der bistatischen Radarbildgebung},
    Author = {Walterscheid, Ingo},
    Editor = {Ender, Prof. Dr. J.},
    ISBN = {978-3-8322-7224-1},
    Location = {Aachen, Germay},
    Publisher = {Shaker Verlag},
    Series = {FHR-Schriftenreihe},
    Url = {http://www.shaker.de/Online-Gesamtkatalog/details.asp?ID=6340638&CC=57212&ISBN=3-8322-7224-0},
    Year = {2008},
    Keywords = {SAR Processing, Bistatic SAR, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Time-Domain Back-Projection, Back-Projection, NuSAR, Airborne SAR, PAMIR, Elektrotechnik Radartechnik Signalverarbeitung Radarsignalverarbeitung},
    Owner = {ofrey},
    Pdf = {../../../docs/walterscheid2008Diss.pdf} 
    }
    


  2. Annelie Wyholt. SAR Image Focus Errors due to Incorrect Geometrical Positioning in Fast Factorized Back-Projection. Licentiatavhandling, Chalmers University of Technology, 2008. Keyword(s): SAR Processing, Autofocus, Time-Domain Back-Projection, TDBP, FFBP, SAR image processing, antenna path parameters, autofocus, fast factorized back-projection, radar imaging, synthetic aperture radar.
    Abstract: Synthetic Aperture Radar, SAR, is an aperture synthesis technique to generate an image of the ground from air or space with high resolution. Signal processing is performed in frequency domain with Fourier Transform techniques, or in time domain with Back Projection techniques. The advantage of Back-Projection processing is that any aperture shape can be handled and the processing can be performed in real time. The Fast Factorized Back Projection algorithm, FFBP, is also computationally efficient and comparable to Fast Fourier Transform methods. When the resolution is near wavelength size the FFBP algorithm is dependent on accurate positioning data and topography information to avoid defocusing due to range errors. Other SAR image formation methods can use an autofocus method to relax the demands on the positioning data or to remove residual phase errors after the image formation. However, none of the existing autofocus methods will fit the way FFBP is executed. Thus a new autofocus method which will be integrated with FFBP is needed. This thesis is focused on the analysis of different range errors that can occur in one merging step in the FFBP processing and how they can be avoided or corrected, topography errors as well as aperture errors. The analysis of aperture geometry errors is built on coordinate transformation matrixes which can be used for every type of geometry error to calculate the corresponding image shift at any location in the image. A few illustrating examples of aperture geometry errors have been analyzed and a method to track the geometry error by measuring the image shift is presented. It is concluded that defocusing due to topography errors will only arise when the subapertures are not co-linear. The defocusing increases with the angle between the subaperture directions, the subaperture length and the size of the topography error. An expression of the accuracy of topography data needed to preserve the focus for different aperture sizes and subaperture tilts is presented. Different subaperture geometry errors will differently give rise to image shifts in the resulting image. As long as there is contrast in the scene such that image shifts can be accurately determined, a focusing preserving processing geometry can be found by correlation measurements. The estimated geometry can differ from the true geometry relative to the ground. If this is the case, the image will be distorted but still be focused which means that the estimated image is just another view of the true image. Image distortions can also be detected with correlation measurements between subaperture images but only if one image is distorted differently than the other.

    @Book{Wyholt2008sif,
    Title = {{SAR} Image Focus Errors due to Incorrect Geometrical Positioning in Fast Factorized Back-Projection},
    Author = {Wyholt, Annelie},
    Publisher = {Licentiatavhandling, Chalmers University of Technology},
    Year = {2008},
    Abstract = {Synthetic Aperture Radar, SAR, is an aperture synthesis technique to generate an image of the ground from air or space with high resolution. Signal processing is performed in frequency domain with Fourier Transform techniques, or in time domain with Back Projection techniques. The advantage of Back-Projection processing is that any aperture shape can be handled and the processing can be performed in real time. The Fast Factorized Back Projection algorithm, FFBP, is also computationally efficient and comparable to Fast Fourier Transform methods. When the resolution is near wavelength size the FFBP algorithm is dependent on accurate positioning data and topography information to avoid defocusing due to range errors. Other SAR image formation methods can use an autofocus method to relax the demands on the positioning data or to remove residual phase errors after the image formation. However, none of the existing autofocus methods will fit the way FFBP is executed. Thus a new autofocus method which will be integrated with FFBP is needed. This thesis is focused on the analysis of different range errors that can occur in one merging step in the FFBP processing and how they can be avoided or corrected, topography errors as well as aperture errors. The analysis of aperture geometry errors is built on coordinate transformation matrixes which can be used for every type of geometry error to calculate the corresponding image shift at any location in the image. A few illustrating examples of aperture geometry errors have been analyzed and a method to track the geometry error by measuring the image shift is presented. It is concluded that defocusing due to topography errors will only arise when the subapertures are not co-linear. The defocusing increases with the angle between the subaperture directions, the subaperture length and the size of the topography error. An expression of the accuracy of topography data needed to preserve the focus for different aperture sizes and subaperture tilts is presented. Different subaperture geometry errors will differently give rise to image shifts in the resulting image. As long as there is contrast in the scene such that image shifts can be accurately determined, a focusing preserving processing geometry can be found by correlation measurements. The estimated geometry can differ from the true geometry relative to the ground. If this is the case, the image will be distorted but still be focused which means that the estimated image is just another view of the true image. Image distortions can also be detected with correlation measurements between subaperture images but only if one image is distorted differently than the other.},
    Keywords = {SAR Processing, Autofocus, Time-Domain Back-Projection, TDBP, FFBP, SAR image processing;antenna path parameters;autofocus;fast factorized back-projection;radar imaging;synthetic aperture radar} 
    }
    


Articles in journal or book chapters

  1. R.G. Baraniuk, E. Candes, R. Nowak, and M. Vetterli. Compressive Sampling [From the Guest Editors]. IEEE Signal Processing Magazine, 25(2):12 -13, March 2008.
    Abstract: The ten articles in this special section provide the reader with specific insights into the basic theory, capabilities, and limitations of compressed sensing (CS). The papers are summarized here.

    @Article{4472238,
    Title = {Compressive Sampling [From the Guest Editors]},
    Author = {Baraniuk, R.G. and Candes, E. and Nowak, R. and Vetterli, M.},
    Doi = {10.1109/MSP.2008.915557},
    ISSN = {1053-5888},
    Month = mar,
    Number = {2},
    Pages = {12 -13},
    Volume = {25},
    Year = {2008},
    Abstract = {The ten articles in this special section provide the reader with specific insights into the basic theory, capabilities, and limitations of compressed sensing (CS). The papers are summarized here.},
    Journal = {IEEE Signal Processing Magazine} 
    }
    


  2. F. Berizzi, M. Martorella, A. Cacciamano, and A. Capria. A Contrast-Based Algorithm For Synthetic Range-Profile Motion Compensation. IEEE Transactions on Geoscience and Remote Sensing, 46(10):3053-3062, October 2008. Keyword(s): motion compensation, radar signal processing, synthetic aperture radarSAR image reconstruction, SNR loss, acceleration distortion effects, asymmetric smearing, contrast based algorithm, contrast optimization, estimation error analysis, low PRF radars, motion compensation technique, radar pulse repetition frequency, range shift, range-profile distortions, stepped frequency radar, stepped frequency waveform, symmetric spreading, synthetic aperture radar, synthetic range profile cost function, synthetic range-profile motion compensation, target motion, target radial acceleration, target radial velocity.
    Abstract: In stepped-frequency radar, target motions produce range-profile distortions. Range shift, signal-to-noise ratio loss, and symmetric spreading are produced by target radial velocity, whereas target radial acceleration is mainly responsible for asymmetric smearing. Acceleration-distortion effects are usually negligible when a high Pulse Repetition Frequency (PRF) is used, although this is not the case for low-PRF radars. In this paper, a new motion-compensation technique based on contrast optimization is proposed. The innovative contributions of this paper are as follows: (1) A theoretical analysis of the distortions produced by target motions on the reconstruction of synthetic aperture radar is provided; (2) the proposed technique compensates both phase terms, which are due to target radial velocity and acceleration; therefore, synthetic range profiles can be focused by processing low-PRF radar returns; (3) a new cost function for the synthetic range profiles (namely, contrast) is defined and used for motion compensation; (4) the proposed technique can be applied to any kind of stepped-frequency waveforms; and (5) an estimation error analysis is performed, first theoretically and then by means of both simulations and real data.

    @Article{4637925,
    Title = {A Contrast-Based Algorithm For Synthetic Range-Profile Motion Compensation},
    Author = {Berizzi, F. and Martorella, M. and Cacciamano, A. and Capria, A.},
    Doi = {10.1109/TGRS.2008.2002576},
    ISSN = {0196-2892},
    Month = {oct},
    Number = {10},
    Pages = {3053-3062},
    Volume = {46},
    Year = {2008},
    Abstract = {In stepped-frequency radar, target motions produce range-profile distortions. Range shift, signal-to-noise ratio loss, and symmetric spreading are produced by target radial velocity, whereas target radial acceleration is mainly responsible for asymmetric smearing. Acceleration-distortion effects are usually negligible when a high Pulse Repetition Frequency (PRF) is used, although this is not the case for low-PRF radars. In this paper, a new motion-compensation technique based on contrast optimization is proposed. The innovative contributions of this paper are as follows: (1) A theoretical analysis of the distortions produced by target motions on the reconstruction of synthetic aperture radar is provided; (2) the proposed technique compensates both phase terms, which are due to target radial velocity and acceleration; therefore, synthetic range profiles can be focused by processing low-PRF radar returns; (3) a new cost function for the synthetic range profiles (namely, contrast) is defined and used for motion compensation; (4) the proposed technique can be applied to any kind of stepped-frequency waveforms; and (5) an estimation error analysis is performed, first theoretically and then by means of both simulations and real data.},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {motion compensation, radar signal processing, synthetic aperture radarSAR image reconstruction, SNR loss, acceleration distortion effects, asymmetric smearing, contrast based algorithm, contrast optimization, estimation error analysis, low PRF radars, motion compensation technique, radar pulse repetition frequency, range shift, range-profile distortions, stepped frequency radar, stepped frequency waveform, symmetric spreading, synthetic aperture radar, synthetic range profile cost function, synthetic range-profile motion compensation, target motion, target radial acceleration, target radial velocity} 
    }
    


  3. Pablo Blanco-Sáchez, Jordi J. Mallorquì, Sergi Duque, and Daniel Monells. The Coherent Pixels Technique (CPT): An Advanced DInSAR Technique for Nonlinear Deformation Monitoring. Pure and Applied Geophysics, 165(6):1167-1193, 2008. Keyword(s): SAR Processing, PSI, Persistent Scatterer Interferometry, Spaceborne SAR, InSAR, DInSAR, Interferometry, Coherernt Pixel Technique, CPT, Orbital SAR, differential interferometry, deformation monitoring.
    Abstract: This paper shows the potential applicability of orbital Synthetic Aperture Radar (SAR) Differential Interferometry (DInSAR) with multiple images for terrain deformation episodes monitoring. This paper is focused on the Coherent Pixels Technique (CPT) developed at the Remote Sensing Laboratory (RSLab) of the Universitat Politecnica de Catalunya (UPC). CPT is able to extract from a stack of differential interferograms the deformation evolution over vast areas during wide spans of time. The former is achieved thanks to the coverage provided by current SAR satellites, like ESA's ERS or ENVISAT, while the latter due to the large archive of images acquired since 1992. An interferogram is formed by the complex product of two SAR images (one complex conjugate) and its phase contains information relative to topography, terrain deformation and atmospheric conditions among others. The goal of differential interferometric processing is to retrieve and separate the different contributions. The processing scheme is composed of three main steps: firstly, the generation of the best interferogram set among all the available images of the zone under study; secondly, the selection of the pixels with reliable phase within the employed interferograms and, thirdly, their phase analysis to calculate, as the main result, their deformation time series within the observation period. In this paper, the Coherent Pixels Technique (CPT) is presented in detail as well as the result of its application in different scenarios. Results reveal its practical utility for detecting and reproducing deformation episodes, providing a valuable tool to the scientific community for the understanding of considerable geological process and to monitor the impact of underground human activity.

    @Article{blancoSanchezMallorquiDuqueMonells2008PSI,
    author = {Blanco-S{\'a}chez, Pablo and Mallorqu{\'i}, Jordi J. and Duque, Sergi and Monells, Daniel},
    title = {The Coherent Pixels Technique ({CPT}): An Advanced {DInSAR} Technique for Nonlinear Deformation Monitoring},
    journal = {Pure and Applied Geophysics},
    year = {2008},
    volume = {165},
    number = {6},
    pages = {1167-1193},
    issn = {0033-4553},
    abstract = {This paper shows the potential applicability of orbital Synthetic Aperture Radar (SAR) Differential Interferometry (DInSAR) with multiple images for terrain deformation episodes monitoring. This paper is focused on the Coherent Pixels Technique (CPT) developed at the Remote Sensing Laboratory (RSLab) of the Universitat Politecnica de Catalunya (UPC). CPT is able to extract from a stack of differential interferograms the deformation evolution over vast areas during wide spans of time. The former is achieved thanks to the coverage provided by current SAR satellites, like ESA's ERS or ENVISAT, while the latter due to the large archive of images acquired since 1992. An interferogram is formed by the complex product of two SAR images (one complex conjugate) and its phase contains information relative to topography, terrain deformation and atmospheric conditions among others. The goal of differential interferometric processing is to retrieve and separate the different contributions. The processing scheme is composed of three main steps: firstly, the generation of the best interferogram set among all the available images of the zone under study; secondly, the selection of the pixels with reliable phase within the employed interferograms and, thirdly, their phase analysis to calculate, as the main result, their deformation time series within the observation period. In this paper, the Coherent Pixels Technique (CPT) is presented in detail as well as the result of its application in different scenarios. Results reveal its practical utility for detecting and reproducing deformation episodes, providing a valuable tool to the scientific community for the understanding of considerable geological process and to monitor the impact of underground human activity.},
    doi = {10.1007/s00024-008-0352-6},
    file = {:blancoSanchezMallorquiDuqueMonells2008PSI.pdf:PDF},
    keywords = {SAR Processing, PSI, Persistent Scatterer Interferometry, Spaceborne SAR, InSAR, DInSAR, Interferometry, Coherernt Pixel Technique, CPT, Orbital SAR; differential interferometry; deformation monitoring},
    owner = {ofrey},
    pdf = {../../../docs/blancoSanchezMallorquiDuqueMonells2008PSI.pdf},
    publisher = {SP Birkh{\"a}user Verlag Basel},
    url = {http://dx.doi.org/10.1007/s00024-008-0352-6},
    
    }
    


  4. Andreas .R. Brenner and Ludwig Roessing. Radar Imaging of Urban Areas by Means of Very High-Resolution SAR and Interferometric SAR. IEEE Trans. Geosci. Remote Sens., 46(10):2971-2982, Oct. 2008. Keyword(s): SAR Processing, InSAR, Interferometry, SAR Interferometry, X-Band, Repeat-Pass Interferometry, Repeat-Pass, Single-Pass, Airborne SAR, PAMIR, Autofocus, Residual Motion Errors, Motion Compensation, MoComp, earthquakes, radar imaging, radar interferometry, remote sensing by radar, synthetic aperture radar, topography (Earth), Forschungsgesellschaft fur Angewandte Naturwissenschaften, Germany, PAMIR, Research Institute for High Frequency Physics and Radar Techniques, Wachtberg, X-band demonstrator, building recognition, building reconstruction, earthquake damage mapping, interferometric SAR sensor, phased array multifunctional imaging radar, radar imaging, radar-based urban analysis, remote-sensing applications, structural image analysis, subdecimeter resolution features, synthetic aperture radar, urban area monitoring, urban elevation models.
    Abstract: In remote-sensing applications, the monitoring of urban areas by means of synthetic aperture radar (SAR) sensors has grown into a valuable and indispensable tool. Although SAR imaging with a spatial resolution down to 1 m is widespread, a resolution as fine as 10 cm and below is offered only by very few SAR sensors worldwide. In this paper, the potential of very high-resolution radar imaging of urban areas by means of SAR and interferometric imaging will be demonstrated and discussed. Results of urban SAR imaging down to subdecimeter resolution will be shown. Even though the immanent layover situation in urban areas is an obstacle to simple image understanding, a remedy can be found by using interferometric SAR imaging. Interferometric results based on very high-resolution SAR images acquired over urban areas, partially with a severe layover situation, will be presented. The corresponding data was acquired with the phased array multifunctional imaging radar (PAMIR), the X-band demonstrator of the Research Institute for High Frequency Physics and Radar Techniques (FHR), Forschungsgesellschaft fur Angewandte Naturwissenschaften (FGAN), Wachtberg, Germany. It can be stated that high-resolution interferometric SAR will be an important basis for upcoming radar-based urban analysis.

    @Article{brennerRoessing2008:InSARPAMIR,
    author = {Brenner, Andreas .R. and Roessing, Ludwig},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    title = {Radar Imaging of Urban Areas by Means of Very High-Resolution SAR and Interferometric SAR},
    year = {2008},
    issn = {0196-2892},
    month = {Oct.},
    number = {10},
    pages = {2971-2982},
    volume = {46},
    abstract = {In remote-sensing applications, the monitoring of urban areas by means of synthetic aperture radar (SAR) sensors has grown into a valuable and indispensable tool. Although SAR imaging with a spatial resolution down to 1 m is widespread, a resolution as fine as 10 cm and below is offered only by very few SAR sensors worldwide. In this paper, the potential of very high-resolution radar imaging of urban areas by means of SAR and interferometric imaging will be demonstrated and discussed. Results of urban SAR imaging down to subdecimeter resolution will be shown. Even though the immanent layover situation in urban areas is an obstacle to simple image understanding, a remedy can be found by using interferometric SAR imaging. Interferometric results based on very high-resolution SAR images acquired over urban areas, partially with a severe layover situation, will be presented. The corresponding data was acquired with the phased array multifunctional imaging radar (PAMIR), the X-band demonstrator of the Research Institute for High Frequency Physics and Radar Techniques (FHR), Forschungsgesellschaft fur Angewandte Naturwissenschaften (FGAN), Wachtberg, Germany. It can be stated that high-resolution interferometric SAR will be an important basis for upcoming radar-based urban analysis.},
    doi = {10.1109/TGRS.2008.920911},
    keywords = {SAR Processing, InSAR, Interferometry, SAR Interferometry, X-Band, Repeat-Pass Interferometry, Repeat-Pass, Single-Pass, Airborne SAR, PAMIR, Autofocus, Residual Motion Errors, Motion Compensation, MoComp,earthquakes, radar imaging, radar interferometry, remote sensing by radar, synthetic aperture radar, topography (Earth), Forschungsgesellschaft fur Angewandte Naturwissenschaften, Germany, PAMIR, Research Institute for High Frequency Physics and Radar Techniques, Wachtberg, X-band demonstrator, building recognition, building reconstruction, earthquake damage mapping, interferometric SAR sensor, phased array multifunctional imaging radar, radar imaging, radar-based urban analysis, remote-sensing applications, structural image analysis, subdecimeter resolution features, synthetic aperture radar, urban area monitoring, urban elevation models},
    owner = {ofrey},
    pdf = {../../../docs/brennerRoessing2008.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4637926&isnumber=4637826},
    
    }
    


  5. Jehanzeb Burki and Christopher F. Barnes. Slant Plane CSAR Processing Using Householder Transform. IEEE Transactions on Image Processing, 17(10):1900-1907, October 2008. Keyword(s): SAR Processing, Circular SAR, Azimuth Focusing, Fourier transforms, radar imaging, synthetic aperture radar, Fourier analysis-based focusing, Householder transform, ground plane circular SAR signal, linear shift-varying system, slant plane CSAR processing, synthetic aperture radar, Adaptive optics, Fourier transforms, History, Image analysis, Image reconstruction, Optical imaging, Optical sensors, Optical signal processing, Radar polarimetry, Synthetic aperture radar, 2-D aperture synthesis, Circular aperture, Fourier optics, Fourier transform, Householder transform, circular synthetic aperture radar (CSAR), synthetic aperture radar (SAR), Algorithms, Fourier Analysis, Image Enhancement, Image Interpretation, Computer-Assisted, Imaging, Three-Dimensional, Radar, Reproducibility of Results, Sensitivity and Specificity.
    Abstract: Fourier analysis-based focusing of synthetic aperture radar (SAR) data collected during circular flight path is a recent advancement in SAR signal processing. This paper uses the Householder transform to obtain a ground plane circular SAR (CSAR) signal phase history from the slant plane CSAR phase history by inverting the linear shift-varying system model, thereby circumventing the need for explicitly computing a pseudo-inverse. The Householder transform has recently been shown to have improved error bounds and stability as an underdetermined and ill-conditioned system solver, and the Householder transform is computationally efficient.

    @Article{burkiBarnesTIP2008CircularSARProcessingUsingHouseholderTransform,
    author = {Burki, Jehanzeb and Barnes, Christopher F.},
    title = {Slant Plane {CSAR} Processing Using {Householder} Transform},
    journal = {IEEE Transactions on Image Processing},
    year = {2008},
    volume = {17},
    number = {10},
    pages = {1900-1907},
    month = oct,
    issn = {1057-7149},
    abstract = {Fourier analysis-based focusing of synthetic aperture radar (SAR) data collected during circular flight path is a recent advancement in SAR signal processing. This paper uses the Householder transform to obtain a ground plane circular SAR (CSAR) signal phase history from the slant plane CSAR phase history by inverting the linear shift-varying system model, thereby circumventing the need for explicitly computing a pseudo-inverse. The Householder transform has recently been shown to have improved error bounds and stability as an underdetermined and ill-conditioned system solver, and the Householder transform is computationally efficient.},
    doi = {10.1109/TIP.2008.2002161},
    file = {:burkiBarnesTIP2008CircularSARProcessingUsingHouseholderTransform.pdf:PDF},
    keywords = {SAR Processing, Circular SAR, Azimuth Focusing, Fourier transforms;radar imaging;synthetic aperture radar;Fourier analysis-based focusing;Householder transform;ground plane circular SAR signal;linear shift-varying system;slant plane CSAR processing;synthetic aperture radar;Adaptive optics;Fourier transforms;History;Image analysis;Image reconstruction;Optical imaging;Optical sensors;Optical signal processing;Radar polarimetry;Synthetic aperture radar;2-D aperture synthesis;Circular aperture;Fourier optics;Fourier transform;Householder transform;circular synthetic aperture radar (CSAR);synthetic aperture radar (SAR);Algorithms;Fourier Analysis;Image Enhancement;Image Interpretation, Computer-Assisted;Imaging, Three-Dimensional;Radar;Reproducibility of Results;Sensitivity and Specificity},
    owner = {ofrey},
    pdf = {../../../docs/burkiBarnesTIP2008CircularSARProcessingUsingHouseholderTransform.pdf},
    
    }
    


  6. Emmanuel J. Candes. The restricted isometry property and its implications for compressed sensing. Comptes Rendus Mathematique, 346(9-10):589-592, 2008. Keyword(s): Compressive Sensing, Compressed Sensing.
    @Article{Candes2008IsometryPropertyCS,
    Title = {The restricted isometry property and its implications for compressed sensing},
    Author = {Emmanuel J. Candes},
    Doi = {10.1016/j.crma.2008.03.014},
    ISSN = {1631-073X},
    Number = {9-10},
    Pages = {589-592},
    Url = {http://www.sciencedirect.com/science/article/pii/S1631073X08000964},
    Volume = {346},
    Year = {2008},
    Journal = {Comptes Rendus Mathematique},
    Keywords = {Compressive Sensing, Compressed Sensing} 
    }
    


  7. E.J. Candes and M.B. Wakin. An Introduction To Compressive Sampling. IEEE Signal Processing Magazine, 25(2):21-30, March 2008. Keyword(s): Relatively few wavelet, compressed sensing, compressive sampling, data acquisition, image recovery, sampling paradigm, sensing paradigm, signal recovery, data acquisition, image processing, signal processing equipment, signal sampling;.
    Abstract: Conventional approaches to sampling signals or images follow Shannon's theorem: the sampling rate must be at least twice the maximum frequency present in the signal (Nyquist rate). In the field of data conversion, standard analog-to-digital converter (ADC) technology implements the usual quantized Shannon representation - the signal is uniformly sampled at or above the Nyquist rate. This article surveys the theory of compressive sampling, also known as compressed sensing or CS, a novel sensing/sampling paradigm that goes against the common wisdom in data acquisition. CS theory asserts that one can recover certain signals and images from far fewer samples or measurements than traditional methods use.

    @Article{4472240,
    Title = {An Introduction To Compressive Sampling},
    Author = {Candes, E.J. and Wakin, M.B.},
    Doi = {10.1109/MSP.2007.914731},
    ISSN = {1053-5888},
    Month = mar,
    Number = {2},
    Pages = {21-30},
    Volume = {25},
    Year = {2008},
    Abstract = {Conventional approaches to sampling signals or images follow Shannon's theorem: the sampling rate must be at least twice the maximum frequency present in the signal (Nyquist rate). In the field of data conversion, standard analog-to-digital converter (ADC) technology implements the usual quantized Shannon representation - the signal is uniformly sampled at or above the Nyquist rate. This article surveys the theory of compressive sampling, also known as compressed sensing or CS, a novel sensing/sampling paradigm that goes against the common wisdom in data acquisition. CS theory asserts that one can recover certain signals and images from far fewer samples or measurements than traditional methods use.},
    Journal = {IEEE Signal Processing Magazine},
    Keywords = {Relatively few wavelet;compressed sensing;compressive sampling;data acquisition;image recovery;sampling paradigm;sensing paradigm;signal recovery;data acquisition;image processing;signal processing equipment;signal sampling;} 
    }
    


  8. D. Cerutti-Maori, J. Klare, A.R. Brenner, and Joachim H. G. Ender. Wide-Area Traffic Monitoring With the SAR/GMTI System PAMIR. IEEE Trans. Geosci. Remote Sens., 46(10):3019-3030, Oct. 2008. Keyword(s): road traffic, synthetic aperture radar, target trackingGround Moving Target Indication mode, SAR-GMTI system, airborne radar sensor PAMIR, positioning accuracy, radial velocity, scan-MTI mode, signal-to-noise ratio, vehicles detection, wide area traffic monitoring experiment.
    Abstract: This paper presents a wide area traffic monitoring experiment under real conditions, using the scan-MTI mode of the airborne radar sensor PAMIR. This flexible GMTI (Ground Moving Target Indication) mode was designed in order to rapidly monitor wide areas for moving targets. The scan operation enables the detection of targets from different aspect angles with a high revisit rate. The parameters (e.g., radial velocity, signal-to-noise ratio, and positioning accuracy) of the detected vehicles are investigated and compared to the expected theoretical GMTI performance. It will be shown that the scan-MTI mode is particularly adapted to perform an efficient wide-area traffic monitoring.

    @Article{4637928,
    author = {Cerutti-Maori, D. and Klare, J. and Brenner, A.R. and Joachim H. G. Ender},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    title = {Wide-Area Traffic Monitoring With the SAR/GMTI System PAMIR},
    year = {2008},
    issn = {0196-2892},
    month = {Oct.},
    number = {10},
    pages = {3019-3030},
    volume = {46},
    abstract = {This paper presents a wide area traffic monitoring experiment under real conditions, using the scan-MTI mode of the airborne radar sensor PAMIR. This flexible GMTI (Ground Moving Target Indication) mode was designed in order to rapidly monitor wide areas for moving targets. The scan operation enables the detection of targets from different aspect angles with a high revisit rate. The parameters (e.g., radial velocity, signal-to-noise ratio, and positioning accuracy) of the detected vehicles are investigated and compared to the expected theoretical GMTI performance. It will be shown that the scan-MTI mode is particularly adapted to perform an efficient wide-area traffic monitoring.},
    doi = {10.1109/TGRS.2008.923026},
    keywords = {road traffic, synthetic aperture radar, target trackingGround Moving Target Indication mode, SAR-GMTI system, airborne radar sensor PAMIR, positioning accuracy, radial velocity, scan-MTI mode, signal-to-noise ratio, vehicles detection, wide area traffic monitoring experiment},
    
    }
    


  9. Karlus A. Câmara de Macedo, Rolf Scheiber, and Alberto Moreira. An Autofocus Approach for Residual Motion Errors With Application to Airborne Repeat-Pass SAR Interferometry. IEEE Transactions on Geoscience and Remote Sensing, 46(10):3151-3162, October 2008. Keyword(s): SAR Processing, Autofocus, Residual Motion Errors, WPCA, Weighted PCA, Weighted Phase Curvature Autofocus, Phase Curvature Autofocus, PCA, Phase Gradient Autofocus, PGA, Repeat-Pass Interferometry, Interferometry, InSAR, D-InSAR, Differential SAR Interferometry, E-SAR, airborne SAR, Baseline Calibration, Tomography, SAR Tomography, deformation, geophysical techniques, synthetic aperture radar, topography (Earth)E-SAR system, German Aerospace Center, airborne repeat-pass SAR Interferometry, autofocus algorithm, autofocus techniques, high-precision navigation system, image processing, interferometric-phase accuracy, phase curvature autofocus, residual motion errors, synthetic-aperture-radar, terrain deformations measurement, weighted least squares phase estimation.
    Abstract: Airborne repeat-pass SAR systems are very sensible to subwavelength deviations from the reference track. To enable repeat-pass interferometry, a high-precision navigation system is needed. Due to the limit of accuracy of such systems, deviations in the order of centimeters remain between the real track and the processed one, causing mainly undesirable phase undulations and misregistration in the interferograms, referred to as residual motion errors. Up to now, only interferometric approaches, as multisquint, are used to compensate for such residual errors. In this paper, we present for the first time the use of the autofocus technique for residual motion errors in the repeat-pass interferometric context. A very robust autofocus technique has to be used to cope with the demands of the repeat-pass applications. We propose a new robust autofocus algorithm based on the weighted least squares phase estimation and the phase curvature autofocus (PCA) extended to the range-dependent case. We call this new algorithm weighted PCA. Different from multisquint, the autofocus approach has the advantage of being able to estimate motion deviations independently, leading to better focused data and correct impulse-response positioning. As a consequence, better coherence and interferometric-phase accuracy are achieved. Repeat-pass interferometry based only on image processing gains in robustness and reliability, since its performance does not deteriorate with time decorrelation and no assumptions need to be made on the interferometric phase. Repeat-pass data of the E-SAR system of the German Aerospace Center (DLR) are used to demonstrate the performance of the proposed approach.

    @Article{deMacedoScheiberMoreira2008:WPCA,
    Title = {{An Autofocus Approach for Residual Motion Errors With Application to Airborne Repeat-Pass SAR Interferometry}},
    Author = {C{\^a}mara de Macedo, Karlus A. and Scheiber, Rolf and Moreira, Alberto},
    Doi = {10.1109/TGRS.2008.924004},
    ISSN = {0196-2892},
    Month = {oct},
    Number = {10},
    Pages = {3151--3162},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4637939&isnumber=4637921},
    Volume = {46},
    Year = {2008},
    Abstract = {Airborne repeat-pass SAR systems are very sensible to subwavelength deviations from the reference track. To enable repeat-pass interferometry, a high-precision navigation system is needed. Due to the limit of accuracy of such systems, deviations in the order of centimeters remain between the real track and the processed one, causing mainly undesirable phase undulations and misregistration in the interferograms, referred to as residual motion errors. Up to now, only interferometric approaches, as multisquint, are used to compensate for such residual errors. In this paper, we present for the first time the use of the autofocus technique for residual motion errors in the repeat-pass interferometric context. A very robust autofocus technique has to be used to cope with the demands of the repeat-pass applications. We propose a new robust autofocus algorithm based on the weighted least squares phase estimation and the phase curvature autofocus (PCA) extended to the range-dependent case. We call this new algorithm weighted PCA. Different from multisquint, the autofocus approach has the advantage of being able to estimate motion deviations independently, leading to better focused data and correct impulse-response positioning. As a consequence, better coherence and interferometric-phase accuracy are achieved. Repeat-pass interferometry based only on image processing gains in robustness and reliability, since its performance does not deteriorate with time decorrelation and no assumptions need to be made on the interferometric phase. Repeat-pass data of the E-SAR system of the German Aerospace Center (DLR) are used to demonstrate the performance of the proposed approach.},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, Autofocus, Residual Motion Errors, WPCA, Weighted PCA, Weighted Phase Curvature Autofocus, Phase Curvature Autofocus, PCA, Phase Gradient Autofocus, PGA, Repeat-Pass Interferometry, Interferometry, InSAR, D-InSAR, Differential SAR Interferometry, E-SAR, airborne SAR, Baseline Calibration, Tomography, SAR Tomography, deformation, geophysical techniques, synthetic aperture radar, topography (Earth)E-SAR system, German Aerospace Center, airborne repeat-pass SAR Interferometry, autofocus algorithm, autofocus techniques, high-precision navigation system, image processing, interferometric-phase accuracy, phase curvature autofocus, residual motion errors, synthetic-aperture-radar, terrain deformations measurement, weighted least squares phase estimation},
    Owner = {ofrey},
    Pdf = {../../../docs/deMacedoScheiberMoreira2008.pdf} 
    }
    


  10. Othmar Frey, Felix Morsdorf, and Erich Meier. Tomographic Imaging of a Forested Area By Airborne Multi-Baseline P-Band SAR. Sensors, Special Issue on Synthetic Aperture Radar, 8(9):5884-5896, September 2008. Keyword(s): SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry.
    Abstract: In recent years, various attempts have been undertaken to obtain information about the structure of forested areas from multi-baseline synthetic aperture radar data. Tomographic processing of such data has been demonstrated for airborne L-band data but the quality of the focused tomographic images is limited by several factors. In particular, the common Fourierbased focusing methods are susceptible to irregular and sparse sampling, two problems, that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. In this paper, a tomographic focusing method based on the time-domain back-projection algorithm is proposed, which maintains the geometric relationship between the original sensor positions and the imaged target and is therefore able to cope with irregular sampling without introducing any approximations with respect to the geometry. The tomographic focusing quality is assessed by analysing the impulse response of simulated point targets and an in-scene corner reflector. And, in particular, several tomographic slices of a volume representing a forested area are given. The respective P-band tomographic data set consisting of eleven flight tracks has been acquired by the airborne E-SAR sensor of the German Aerospace Center (DLR).

    @Article{freyMorsdorfMeier08:SensorsTomo,
    author = {Othmar Frey and Felix Morsdorf and Erich Meier},
    title = {Tomographic Imaging of a Forested Area By Airborne Multi-Baseline {P}-Band {SAR}},
    journal = {Sensors, Special Issue on Synthetic Aperture Radar},
    year = {2008},
    volume = {8},
    number = {9},
    pages = {5884--5896},
    month = sep,
    abstract = {In recent years, various attempts have been undertaken to obtain information about the structure of forested areas from multi-baseline synthetic aperture radar data. Tomographic processing of such data has been demonstrated for airborne L-band data but the quality of the focused tomographic images is limited by several factors. In particular, the common Fourierbased focusing methods are susceptible to irregular and sparse sampling, two problems, that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. In this paper, a tomographic focusing method based on the time-domain back-projection algorithm is proposed, which maintains the geometric relationship between the original sensor positions and the imaged target and is therefore able to cope with irregular sampling without introducing any approximations with respect to the geometry. The tomographic focusing quality is assessed by analysing the impulse response of simulated point targets and an in-scene corner reflector. And, in particular, several tomographic slices of a volume representing a forested area are given. The respective P-band tomographic data set consisting of eleven flight tracks has been acquired by the airborne E-SAR sensor of the German Aerospace Center (DLR).},
    doi = {10.3390/s8095884},
    editor = {Daniele Riccio},
    file = {:freyMorsdorfMeier08_SensorsTomo.pdf:PDF},
    keywords = {SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMorsdorfMeierSENSORS2008.pdf},
    url = {http://www.mdpi.org/sensors/papers/s8095884.pdf},
    
    }
    


  11. José-Tomás González-Partida, Pablo Almorox-González, Mateo Burgos-Garcìa, and Blas-Pablo Dorta-Naranjo. SAR System for UAV Operation with Motion Error Compensation beyond the Resolution Cell. Sensors, Special Issue on Synthetic Aperture Radar, 8(5):3384-3405, 2008. Keyword(s): SAR Processing, Motion Compensation, MoComp, Airborne SAR, UAV, Unmanned Airborne Vehicle, LFM-CW, Continuous Wave SAR, Phase Gradient Autofocus, Autofocus, PGA, Range Alignment, Residual Motion Errors, mmW SAR, mmW, Ka-Band SAR.
    Abstract: This paper presents an experimental Synthetic Aperture Radar (SAR) system that is under development in the Universidad Politecnica de Madrid. The system uses Linear Frequency Modulated Continuous Wave (LFM-CW) radar with a two antenna configuration for transmission and reception. The radar operates in the millimeter-wave band with a maximum transmitted bandwidth of 2 GHz. The proposed system is being developed for Unmanned Aerial Vehicle (UAV) operation. Motion errors in UAV operation can be critical. Therefore, this paper proposes a method for focusing SAR images with movement errors larger than the resolution cell. Typically, this problem is solved using two processing steps: first, coarse motion compensation based on the information provided by an Inertial Measuring Unit (IMU); and second, fine motion compensation for the residual errors within the resolution cell based on the received raw data. The proposed technique tries to focus the image without using data of an IMU. The method is based on a combination of the well known Phase Gradient Autofocus (PGA) for SAR imagery and typical algorithms for translational motion compensation on Inverse SAR (ISAR). This paper shows the first real experiments for obtaining high resolution SAR images using a car as a mobile platform for our radar.

    @Article{gonzalezPartidaAlmoroxGonzalezBurgosGarciaDortaNaranjo2008:UAVMoCo,
    author = {Jos{\'e}-Tom{\'a}s Gonz{\'a}lez-Partida and Pablo Almorox-Gonz{\'a}lez and Mateo Burgos-Garc\'{\i}a and Blas-Pablo Dorta-Naranjo},
    journal = {Sensors, Special Issue on Synthetic Aperture Radar},
    title = {{SAR} System for {UAV} Operation with Motion Error Compensation beyond the Resolution Cell},
    year = {2008},
    number = {5},
    pages = {3384--3405},
    volume = {8},
    abstract = {This paper presents an experimental Synthetic Aperture Radar (SAR) system that is under development in the Universidad Politecnica de Madrid. The system uses Linear Frequency Modulated Continuous Wave (LFM-CW) radar with a two antenna configuration for transmission and reception. The radar operates in the millimeter-wave band with a maximum transmitted bandwidth of 2 GHz. The proposed system is being developed for Unmanned Aerial Vehicle (UAV) operation. Motion errors in UAV operation can be critical. Therefore, this paper proposes a method for focusing SAR images with movement errors larger than the resolution cell. Typically, this problem is solved using two processing steps: first, coarse motion compensation based on the information provided by an Inertial Measuring Unit (IMU); and second, fine motion compensation for the residual errors within the resolution cell based on the received raw data. The proposed technique tries to focus the image without using data of an IMU. The method is based on a combination of the well known Phase Gradient Autofocus (PGA) for SAR imagery and typical algorithms for translational motion compensation on Inverse SAR (ISAR). This paper shows the first real experiments for obtaining high resolution SAR images using a car as a mobile platform for our radar.},
    keywords = {SAR Processing, Motion Compensation, MoComp, Airborne SAR, UAV, Unmanned Airborne Vehicle, LFM-CW, Continuous Wave SAR, Phase Gradient Autofocus, Autofocus, PGA, Range Alignment, Residual Motion Errors, mmW SAR,mmW,Ka-Band SAR},
    owner = {ofrey},
    pdf = {../../../docs/gonzalezPartidaAlmoroxGonzalezBurgosGarciaDortaNaranjo2008.pdf},
    url = {http://www.mdpi.org/sensors/papers/s8053384.pdf},
    
    }
    


  12. Andrew Hooper. A multi-temporal InSAR method incorporating both persistent scatterer and small baseline approaches. Geophysical Research Letters, 35(16), 2008. Keyword(s): MT-InSAR, PSI, SBAS.
    Abstract: Synthetic aperture radar (SAR) interferometry is a technique that provides high-resolution measurements of the ground displacement associated with many geophysical processes. Advanced techniques involving the simultaneous processing of multiple SAR acquisitions in time increase the number of locations where a deformation signal can be extracted and reduce associated error. Currently there are two broad categories of algorithms for processing multiple acquisitions, persistent scatterer and small baseline methods, which are optimized for different models of scattering. However, the scattering characteristics of real terrains usually lay between these two end-member models. I present here a new method that combines both approaches, to extract the deformation signal at more points and with higher overall signal-to-noise ratio than can either approach alone. I apply the combined method to data acquired over Eyjafjallaj\"okull volcano in Iceland, and detect time-varying ground displacements associated with two intrusion events.

    @Article{hooperGRL2008MultitemporalInSARWithPSIandSBAS,
    author = {Andrew Hooper},
    title = {A multi-temporal {InSAR} method incorporating both persistent scatterer and small baseline approaches},
    journal = {Geophysical Research Letters},
    year = {2008},
    volume = {35},
    number = {16},
    abstract = {Synthetic aperture radar (SAR) interferometry is a technique that provides high-resolution measurements of the ground displacement associated with many geophysical processes. Advanced techniques involving the simultaneous processing of multiple SAR acquisitions in time increase the number of locations where a deformation signal can be extracted and reduce associated error. Currently there are two broad categories of algorithms for processing multiple acquisitions, persistent scatterer and small baseline methods, which are optimized for different models of scattering. However, the scattering characteristics of real terrains usually lay between these two end-member models. I present here a new method that combines both approaches, to extract the deformation signal at more points and with higher overall signal-to-noise ratio than can either approach alone. I apply the combined method to data acquired over Eyjafjallaj\"okull volcano in Iceland, and detect time-varying ground displacements associated with two intrusion events.},
    doi = {10.1029/2008GL034654},
    eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2008GL034654},
    keywords = {MT-InSAR, PSI, SBAS},
    owner = {ofrey},
    url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2008GL034654},
    
    }
    


  13. S. Jaruwatanadilok and A. Ishimaru. Electromagnetic Coherent Tomography Array Imaging in Random Scattering Media. IEEE Antennas and Wireless Propagation Letters, 7:524-527, 2008. Keyword(s): SAR Processing, SAR Tomography, Tomography, Monte Carlo method, array processing method, discrete random media, electromagnetic coherent tomography array imaging, optical coherence tomography, random scattering media, Monte Carlo methods, optical tomography, random media;.
    Abstract: Imaging through discrete random media is an important problem in several applications such as medicine, remote sensing, and security. Discrete random media create scattering which deteriorates the quality of the image and there have been several efforts to mitigate the problem. We propose an array processing method called coherence tomography array (CTA) whose algorithm is derived from that of optical coherence tomography. We use the Monte Carlo method to simulate the imaging scenarios in random scattering media. The results show that CTA can be used to alleviate the clutter effects from discrete random scatterers.

    @Article{4623153,
    author = {Jaruwatanadilok, S. and Ishimaru, A.},
    journal = {IEEE Antennas and Wireless Propagation Letters},
    title = {Electromagnetic Coherent Tomography Array Imaging in Random Scattering Media},
    year = {2008},
    issn = {1536-1225},
    pages = {524-527},
    volume = {7},
    abstract = {Imaging through discrete random media is an important problem in several applications such as medicine, remote sensing, and security. Discrete random media create scattering which deteriorates the quality of the image and there have been several efforts to mitigate the problem. We propose an array processing method called coherence tomography array (CTA) whose algorithm is derived from that of optical coherence tomography. We use the Monte Carlo method to simulate the imaging scenarios in random scattering media. The results show that CTA can be used to alleviate the clutter effects from discrete random scatterers.},
    doi = {10.1109/LAWP.2008.2005653},
    keywords = {SAR Processing, SAR Tomography, Tomography, Monte Carlo method;array processing method;discrete random media;electromagnetic coherent tomography array imaging;optical coherence tomography;random scattering media;Monte Carlo methods;optical tomography;random media;},
    
    }
    


  14. Michael Jehle, Donat Perler, David Small, Adrian Schubert, and Erich Meier. Estimation of Atmospheric Path Delays in TerraSAR-X Data using Models vs. Measurements. Sensors, 8(12):8479-8491, 2008. Keyword(s): SAR Processing, Ionosphere, TEC, Total Electron Content, Troposphere, Path Delay.
    @Article{jehlePerlerSmallSchubertMeier2008:EstimPathDelay,
    author = {Jehle, Michael and Perler, Donat and Small, David and Schubert, Adrian and Meier, Erich},
    title = {Estimation of Atmospheric Path Delays in {TerraSAR-X} Data using Models vs. Measurements},
    journal = {Sensors},
    year = {2008},
    volume = {8},
    number = {12},
    pages = {8479-8491},
    issn = {1424-8220},
    doi = {10.3390/s8128479},
    file = {:jehlePerlerSmallSchubertMeier2008EstimPathDelay.pdf:PDF},
    keywords = {SAR Processing, Ionosphere, TEC, Total Electron Content, Troposphere, Path Delay},
    
    }
    


  15. Shi Jun, Xiaoling Zhang, and Jianyu Yang. Principle and Methods on Bistatic SAR Signal Processing via Time Correlation. IEEE Trans. Geosci. Remote Sens., 46(10):3163-3178, Oct. 2008. Keyword(s): fast Fourier transforms, geophysical signal processing, radar imaging, radar signal processing, remote sensing by radar, synthetic aperture radar3D scene space ambiguity problem, AVME, RVME, SAR image shifting, SAR image space bases, absolute velocity measurement error, ambiguity region, bistatic SAR 2D PSF, bistatic SAR angular velocity direction, bistatic SAR image space, bistatic SAR signal processing, inverse fast Fourier transform, motion measurement error effects, perspective line, perspective operator, point spread function, range Doppler algorithm, relative velocity measurement error, scaled IFFT, space truncation error, synthetic aperture radar, time correlation radar signal processing, translational variant bistatic SAR imaging method.
    Abstract: In this paper, we discuss the mapping between the 3-D scene space and the bistatic synthetic aperture radar (SAR) image space and show that when the direction of the angular velocity of the bistatic SAR remains constant, the process of bistatic SAR imaging can be approximately modeled as a perspective operator from the 3-D scene space to the 2-D image space, and the perspective line is perpendicular to the plane determined by the composition direction of the T/R line of sight and the composition direction of the angular velocity of the T/R platform. Then, we show that the 2-D point spread function of the bistatic SAR is determined not only by the range and ldquoazimuthrdquo resolutions but also by the geometry of the bistatic SAR and the bases of the SAR image space, and the concept ldquoambiguity regionrdquo is introduced to describe the ambiguity problem in the 3-D scene space. Then, the range-Doppler algorithm is discussed, and a new translational-variant bistatic SAR imaging method is proposed, which uses the scaled inverse fast Fourier transform (IFFT) technique to eliminate the translational-variant feature of the SAR space resolution. The space truncation error of this new algorithm is discussed to analyze the depth of focus of the scaled IFFT bistatic SAR imaging algorithms, and we find that the upper bounce of the space truncation error is proportional to the square of the distance from the scatterer to the T/R platforms. Last, the effects of motion measurement errors are discussed in detail, and, through theoretical analysis and numerical experiments, we show that the absolute position measurement error, the baseline measurement error, the perpendicular (vertical) component of the absolute velocity measurement error (AVME), and the perpendicular component of the relative velocity measurement error (RVME) cause SAR image shifting in the image space mainly, and the parallel component of the AVME and the parallel component of the RVME cause the SAR image to s- - everely defocus.

    @Article{junZhangYang2008:Bistatic,
    author = {Shi Jun and Xiaoling Zhang and Jianyu Yang},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    title = {Principle and Methods on Bistatic SAR Signal Processing via Time Correlation},
    year = {2008},
    issn = {0196-2892},
    month = {Oct.},
    number = {10},
    pages = {3163-3178},
    volume = {46},
    abstract = {In this paper, we discuss the mapping between the 3-D scene space and the bistatic synthetic aperture radar (SAR) image space and show that when the direction of the angular velocity of the bistatic SAR remains constant, the process of bistatic SAR imaging can be approximately modeled as a perspective operator from the 3-D scene space to the 2-D image space, and the perspective line is perpendicular to the plane determined by the composition direction of the T/R line of sight and the composition direction of the angular velocity of the T/R platform. Then, we show that the 2-D point spread function of the bistatic SAR is determined not only by the range and ldquoazimuthrdquo resolutions but also by the geometry of the bistatic SAR and the bases of the SAR image space, and the concept ldquoambiguity regionrdquo is introduced to describe the ambiguity problem in the 3-D scene space. Then, the range-Doppler algorithm is discussed, and a new translational-variant bistatic SAR imaging method is proposed, which uses the scaled inverse fast Fourier transform (IFFT) technique to eliminate the translational-variant feature of the SAR space resolution. The space truncation error of this new algorithm is discussed to analyze the depth of focus of the scaled IFFT bistatic SAR imaging algorithms, and we find that the upper bounce of the space truncation error is proportional to the square of the distance from the scatterer to the T/R platforms. Last, the effects of motion measurement errors are discussed in detail, and, through theoretical analysis and numerical experiments, we show that the absolute position measurement error, the baseline measurement error, the perpendicular (vertical) component of the absolute velocity measurement error (AVME), and the perpendicular component of the relative velocity measurement error (RVME) cause SAR image shifting in the image space mainly, and the parallel component of the AVME and the parallel component of the RVME cause the SAR image to s- - everely defocus.},
    doi = {10.1109/TGRS.2008.920369},
    keywords = {fast Fourier transforms, geophysical signal processing, radar imaging, radar signal processing, remote sensing by radar, synthetic aperture radar3D scene space ambiguity problem, AVME, RVME, SAR image shifting, SAR image space bases, absolute velocity measurement error, ambiguity region, bistatic SAR 2D PSF, bistatic SAR angular velocity direction, bistatic SAR image space, bistatic SAR signal processing, inverse fast Fourier transform, motion measurement error effects, perspective line, perspective operator, point spread function, range Doppler algorithm, relative velocity measurement error, scaled IFFT, space truncation error, synthetic aperture radar, time correlation radar signal processing, translational variant bistatic SAR imaging method},
    
    }
    


  16. Jong-Sen Lee, T.L. Ainsworth, J.P. Kelly, and C. Lopez-Martinez. Evaluation and Bias Removal of Multilook Effect on Entropy/Alpha/Anisotropy in Polarimetric SAR Decomposition. IEEE Trans. Geosci. Remote Sens., 46(10):3039-3052, Oct. 2008. Keyword(s): Monte Carlo methods, geophysical techniques, radar interferometry, radar polarimetry, remote sensing by radar, synthetic aperture radar, vegetationGerman Aerospace Research Center, JPL, Jet Propulsion Laboratory, L-band Advanced Land Observing Satellite, Monte Carlo simulation, airborne X-band polarimetric SAR, airborne interferometric SAR, alpha estimation, anisotropy estimation, bias removal algorithm, entropy estimation, forest, geophysical parameter estimation, grassland, multilook processing, phased array type L-band SAR, polarimetric SAR decomposition, scattering mechanisms, synthetic aperture radar, urban returns.
    Abstract: Entropy, alpha, and anisotropy (H/alpha/A) of the polarimetric target decomposition have been an effective and popular tool for polarimetric synthetic aperture radar (SAR) image analysis and for a geophysical parameter estimation. However, multilook processing can severely affect the values of these parameters. In this paper, a Monte Carlo simulation is used to evaluate and remove the bias generated by the multilook effect on these parameters for various media composed of grassland, forest, and urban returns. Due to insufficient averaging, entropy is underestimated, and anisotropy is overestimated. We also found that the bias in the alpha angle can be either underestimated or overestimated depending on scattering mechanisms. Based on simulation results, efficient bias removal procedures have been developed. In particular, the entropy bias can be precisely corrected, and the amount of correction is independent of the radar frequency and SAR systems. Data from L-band Advanced Land Observing Satellite/phased array type L-band SAR, German Aerospace Research Center (DLR)/enhanced SAR, Jet Propulsion Laboratory (JPL)/airborne SAR, and X-band polarimetric and interferometric SAR are used for demonstration in this paper.

    @Article{4637955,
    author = {Jong-Sen Lee and Ainsworth, T.L. and Kelly, J.P. and Lopez-Martinez, C.},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    title = {Evaluation and Bias Removal of Multilook Effect on Entropy/Alpha/Anisotropy in Polarimetric SAR Decomposition},
    year = {2008},
    issn = {0196-2892},
    month = {Oct.},
    number = {10},
    pages = {3039-3052},
    volume = {46},
    abstract = {Entropy, alpha, and anisotropy (H/alpha/A) of the polarimetric target decomposition have been an effective and popular tool for polarimetric synthetic aperture radar (SAR) image analysis and for a geophysical parameter estimation. However, multilook processing can severely affect the values of these parameters. In this paper, a Monte Carlo simulation is used to evaluate and remove the bias generated by the multilook effect on these parameters for various media composed of grassland, forest, and urban returns. Due to insufficient averaging, entropy is underestimated, and anisotropy is overestimated. We also found that the bias in the alpha angle can be either underestimated or overestimated depending on scattering mechanisms. Based on simulation results, efficient bias removal procedures have been developed. In particular, the entropy bias can be precisely corrected, and the amount of correction is independent of the radar frequency and SAR systems. Data from L-band Advanced Land Observing Satellite/phased array type L-band SAR, German Aerospace Research Center (DLR)/enhanced SAR, Jet Propulsion Laboratory (JPL)/airborne SAR, and X-band polarimetric and interferometric SAR are used for demonstration in this paper.},
    doi = {10.1109/TGRS.2008.922033},
    keywords = {Monte Carlo methods, geophysical techniques, radar interferometry, radar polarimetry, remote sensing by radar, synthetic aperture radar, vegetationGerman Aerospace Research Center, JPL, Jet Propulsion Laboratory, L-band Advanced Land Observing Satellite, Monte Carlo simulation, airborne X-band polarimetric SAR, airborne interferometric SAR, alpha estimation, anisotropy estimation, bias removal algorithm, entropy estimation, forest, geophysical parameter estimation, grassland, multilook processing, phased array type L-band SAR, polarimetric SAR decomposition, scattering mechanisms, synthetic aperture radar, urban returns},
    
    }
    


  17. Lianlin Li and Fang Li. Ionosphere tomography based on spaceborne SAR. Advances in Space Research, 42(7):1187-1193, October 2008. Keyword(s): SAR Processing, Ionosphere tomography, Spaceborne SAR, Electron density isolines, Inverse scattering technique for multi-layered random surfaces, Method of moment, MoM, TEC, Total Electron Content, CT, computerized tomography.
    Abstract: Two models of ionosphere tomography based on spaceborne SAR (Synthetic Aperture Radar) are proposed. For HF-SAR the signal with sweeping frequency lower than the characteristic frequency of ionosphere will be scatted during the ionosphere propagation and completely reflected at a corresponding height. The ionospheric electron density isolines looked as series of random surfaces can be reconstructed from the HF-SAR echoes by using the inverse scattering technique for layered rough surfaces and the method of moment (MoM). The numerical simulation show that due to the MoM can provide a full wave solution, the ionosphere tomography with high resolution can be obtained as long as enough sampling data of HF-SAR echoes are used. For VHF/UHF/P/L-band SAR the TEC (Total Electron Content) can be obtained from the SAR echoes scattered by some strong point targets (such as the calibrators, etc.) appeared in the SAR imaged ground region, and the ionosphere tomography can be performed by CT technique.

    @Article{lili2008:IonoTomoSAR,
    Title = {Ionosphere tomography based on spaceborne SAR},
    Author = {Li, Lianlin and Li, Fang},
    Month = {oct},
    Number = {7},
    Pages = {1187--1193},
    Url = {http://www.sciencedirect.com/science/article/B6V3S-4R8H1XF-2/2/dd51165940e6c27023b473430dfddd6e},
    Volume = {42},
    Year = {2008},
    Abstract = {Two models of ionosphere tomography based on spaceborne SAR (Synthetic Aperture Radar) are proposed. For HF-SAR the signal with sweeping frequency lower than the characteristic frequency of ionosphere will be scatted during the ionosphere propagation and completely reflected at a corresponding height. The ionospheric electron density isolines looked as series of random surfaces can be reconstructed from the HF-SAR echoes by using the inverse scattering technique for layered rough surfaces and the method of moment (MoM). The numerical simulation show that due to the MoM can provide a full wave solution, the ionosphere tomography with high resolution can be obtained as long as enough sampling data of HF-SAR echoes are used. For VHF/UHF/P/L-band SAR the TEC (Total Electron Content) can be obtained from the SAR echoes scattered by some strong point targets (such as the calibrators, etc.) appeared in the SAR imaged ground region, and the ionosphere tomography can be performed by CT technique.},
    Journal = {Advances in Space Research},
    Keywords = {SAR Processing, Ionosphere tomography, Spaceborne SAR, Electron density isolines, Inverse scattering technique for multi-layered random surfaces, Method of moment, MoM, TEC, Total Electron Content, CT, computerized tomography},
    Owner = {ofrey},
    Pdf = {../../../docs/lili2008.pdf} 
    }
    


  18. Fabrizio Lombardini and Matteo Pardini. 3-D SAR Tomography: The Multibaseline Sector Interpolation Approach. IEEE Geoscience and Remote Sensing Letters, 5(4):630-634, Oct. 2008. Keyword(s): SAR Processing, Tomography, SAR Tomography, Multi-baseline SAR, Interpolation, Sector Interpolation, 3-D imaging, SAR Interferometry, Interferometry, InSAR, Spectral Analysis, Electromagnetic Tomography, Signal Sampling.
    Abstract: Multibaseline (MB) synthetic aperture radar (SAR) tomography is a promising mode of SAR interferometry, allowing full 3-D imaging of volumetric and layover scatterers in place of a single elevation estimation capability for each SAR cell . However, Fourier-based MB SAR tomography is generally affected by unsatisfactory imaging quality due to a typically low number of baselines with irregular distribution. In this paper, we improve the basic elevation focusing technique by reconstructing a set of uniform baselines data exploiting in the interpolation step the ancillary information about the extension of a height sector which contains all the scatterers. This a priori information can be derived from the knowledge of the kind of the observed scenario (e.g., forest or urban). To demonstrate the concept, an imaging enhancement analysis is carried out by simulation.

    @Article{lombardiniPardini2008:Tomo,
    author = {Lombardini, Fabrizio and Pardini, Matteo},
    journal = {IEEE Geoscience and Remote Sensing Letters},
    title = {{3-D SAR Tomography: The Multibaseline Sector Interpolation Approach}},
    year = {2008},
    issn = {1545-598X},
    month = {Oct.},
    number = {4},
    pages = {630-634},
    volume = {5},
    abstract = {Multibaseline (MB) synthetic aperture radar (SAR) tomography is a promising mode of SAR interferometry, allowing full 3-D imaging of volumetric and layover scatterers in place of a single elevation estimation capability for each SAR cell . However, Fourier-based MB SAR tomography is generally affected by unsatisfactory imaging quality due to a typically low number of baselines with irregular distribution. In this paper, we improve the basic elevation focusing technique by reconstructing a set of uniform baselines data exploiting in the interpolation step the ancillary information about the extension of a height sector which contains all the scatterers. This a priori information can be derived from the knowledge of the kind of the observed scenario (e.g., forest or urban). To demonstrate the concept, an imaging enhancement analysis is carried out by simulation.},
    doi = {10.1109/LGRS.2008.2001283},
    keywords = {SAR Processing, Tomography, SAR Tomography, Multi-baseline SAR, Interpolation, Sector Interpolation, 3-D imaging, SAR Interferometry, Interferometry, InSAR, Spectral Analysis, Electromagnetic Tomography, Signal Sampling},
    owner = {ofrey},
    pdf = {../../../docs/lombardiniPardini2008.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4656455&isnumber=4656438},
    
    }
    


  19. Alberto Martinez-Vazquez and Joaquim Fortuny-Guasch. A GB-SAR Processor for Snow Avalanche Identification. IEEE Trans. Geosci. Remote Sens., 46(11):3948-3956, November 2008. Keyword(s): SAR Processing, GBSAR, ground-based radar, ground-based SAR, feature extraction, geomorphology, geophysical techniques, geophysics computing, image classification, image segmentation, risk management, snow, synthetic aperture radar, features extraction, ground-based SAR processor, image thresholding, morphological filters, object classification, risk assessment, snow avalanches detection, snow avalanches identification, synthetic aperture radar images, Event detection, Feature extraction, Filters, Monitoring, Object detection, Radar detection, Snow, Statistics, Synthetic aperture radar, Testing, Classification, coherence, ground-based synthetic aperture radar (GBSAR), snow avalanche.
    Abstract: An algorithm for the automatic detection and classification of snow avalanches has been developed and assessed through the archive of synthetic aperture radar (SAR) images acquired during six winter campaigns with a ground-based linear SAR. The scheme, based on the following classic steps: 1) detection; 2) features extraction; and 3) object classification, is fully described in this paper, representing the first attempt to implement a semiautomatic near-real-time operational snow avalanche monitoring tool by SAR. Detection of possible avalanche events is performed by the combined application of thresholding and morphological filters to the differential coherence of consecutive images. Classification of events likely to be snow avalanches is based on statistics extracted from the whole image and features associated to the single regions. Tests have been conducted over more than 60 000 images. Results show a drastic reduction on the images to manually supervise (2.2%). With a 9% false-negative rate and 60% accuracy over the 2.2% of images to examine, the processor represents an interesting support tool for the daily operations of avalanche risk assessment in a commercial ski resort.

    @Article{martinezVazquezFortunyGuaschTGRS2008GBSARSnowAvalanche,
    author = {Martinez-Vazquez, Alberto and Fortuny-Guasch, Joaquim},
    title = {A {GB-SAR} Processor for Snow Avalanche Identification},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {2008},
    volume = {46},
    number = {11},
    pages = {3948-3956},
    month = nov,
    issn = {0196-2892},
    abstract = {An algorithm for the automatic detection and classification of snow avalanches has been developed and assessed through the archive of synthetic aperture radar (SAR) images acquired during six winter campaigns with a ground-based linear SAR. The scheme, based on the following classic steps: 1) detection; 2) features extraction; and 3) object classification, is fully described in this paper, representing the first attempt to implement a semiautomatic near-real-time operational snow avalanche monitoring tool by SAR. Detection of possible avalanche events is performed by the combined application of thresholding and morphological filters to the differential coherence of consecutive images. Classification of events likely to be snow avalanches is based on statistics extracted from the whole image and features associated to the single regions. Tests have been conducted over more than 60 000 images. Results show a drastic reduction on the images to manually supervise (2.2%). With a 9% false-negative rate and 60% accuracy over the 2.2% of images to examine, the processor represents an interesting support tool for the daily operations of avalanche risk assessment in a commercial ski resort.},
    doi = {10.1109/TGRS.2008.2001387},
    file = {:martinezVazquezFortunyGuaschTGRS2008GBSARSnowAvalanche.pdf:PDF},
    keywords = {SAR Processing, GBSAR, ground-based radar, ground-based SAR, feature extraction;geomorphology;geophysical techniques;geophysics computing;image classification;image segmentation;risk management;snow;synthetic aperture radar;features extraction;ground-based SAR processor;image thresholding;morphological filters;object classification;risk assessment;snow avalanches detection;snow avalanches identification;synthetic aperture radar images;Event detection;Feature extraction;Filters;Monitoring;Object detection;Radar detection;Snow;Statistics;Synthetic aperture radar;Testing;Classification;coherence;ground-based synthetic aperture radar (GBSAR);snow avalanche},
    pdf = {../../../docs/martinezVazquezFortunyGuaschTGRS2008GBSARSnowAvalanche.pdf},
    
    }
    


  20. Franz J. Meyer and J.B. Nicoll. Prediction, Detection, and Correction of Faraday Rotation in Full-Polarimetric L-Band SAR Data. IEEE Trans. Geosci. Remote Sens., 46(10):3076-3086, Oct. 2008. Keyword(s): Faraday effect, electromagnetic wave polarisation, ionospheric disturbances, ionospheric electromagnetic wave propagation, ionospheric techniques, radar polarimetry, radiowave propagation, remote sensing by radar, spaceborne radar, synthetic aperture radarAdvanced Land Observing Satellite, Faraday rotation correction, Faraday rotation detection, Faraday rotation estimation, Faraday rotation prediction, PALSAR, SAR data quality degradation, data continuity, full polarimetric L-band SAR data, geophysical parameter recovery accuracy, kilometer scale ionospheric disturbances, spaceborne L-band SAR instrument, synthetic aperture radar.
    Abstract: With the synthetic aperture radar (SAR) sensor PALSAR onboard the Advanced Land Observing Satellite, a new full-polarimetric spaceborne L-band SAR instrument has been launched into orbit. At L-band, Faraday rotation (FR) can reach significant values, degrading the quality of the received SAR data. One-way rotations exceeding 25 deg are likely to happen during the lifetime of PALSAR, which will significantly reduce the accuracy of geophysical parameter recovery if uncorrected. Therefore, the estimation and correction of FR effects is a prerequisite for data quality and continuity. In this paper, methods for estimating FR are presented and analyzed. The first unambiguous detection of FR in SAR data is presented. A set of real data examples indicates the quality and sensitivity of FR estimation from PALSAR data, allowing the measurement of FR with high precision in areas where such measurements were previously inaccessible. In examples, we present the detection of kilometer-scale ionospheric disturbances, a spatial scale that is not detectable by ground-based GPS measurements. An FR prediction method is presented and validated. Approaches to correct for the estimated FR effects are applied, and their effectiveness is tested on real data.

    @Article{meyerNicoll2008:FaradayRotation,
    author = {Meyer, Franz J. and Nicoll, J.B.},
    title = {Prediction, Detection, and Correction of Faraday Rotation in Full-Polarimetric L-Band SAR Data},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {2008},
    volume = {46},
    number = {10},
    pages = {3076-3086},
    month = {Oct.},
    issn = {0196-2892},
    abstract = {With the synthetic aperture radar (SAR) sensor PALSAR onboard the Advanced Land Observing Satellite, a new full-polarimetric spaceborne L-band SAR instrument has been launched into orbit. At L-band, Faraday rotation (FR) can reach significant values, degrading the quality of the received SAR data. One-way rotations exceeding 25 deg are likely to happen during the lifetime of PALSAR, which will significantly reduce the accuracy of geophysical parameter recovery if uncorrected. Therefore, the estimation and correction of FR effects is a prerequisite for data quality and continuity. In this paper, methods for estimating FR are presented and analyzed. The first unambiguous detection of FR in SAR data is presented. A set of real data examples indicates the quality and sensitivity of FR estimation from PALSAR data, allowing the measurement of FR with high precision in areas where such measurements were previously inaccessible. In examples, we present the detection of kilometer-scale ionospheric disturbances, a spatial scale that is not detectable by ground-based GPS measurements. An FR prediction method is presented and validated. Approaches to correct for the estimated FR effects are applied, and their effectiveness is tested on real data.},
    doi = {10.1109/TGRS.2008.2003002},
    file = {:meyerNicoll2008FaradayRotation.pdf:PDF},
    keywords = {Faraday effect, electromagnetic wave polarisation, ionospheric disturbances, ionospheric electromagnetic wave propagation, ionospheric techniques, radar polarimetry, radiowave propagation, remote sensing by radar, spaceborne radar, synthetic aperture radarAdvanced Land Observing Satellite, Faraday rotation correction, Faraday rotation detection, Faraday rotation estimation, Faraday rotation prediction, PALSAR, SAR data quality degradation, data continuity, full polarimetric L-band SAR data, geophysical parameter recovery accuracy, kilometer scale ionospheric disturbances, spaceborne L-band SAR instrument, synthetic aperture radar},
    
    }
    


  21. Andrea Monti-Guarnieri and Stefano Tebaldini. On the Exploitation of Target Statistics for SAR Interferometry Applications. IEEE Transactions on Geoscience and Remote Sensing, 46(11):3436-3443, November 2008. Keyword(s): SAR Processing, Phase Linking, SAR Tomography, geophysical techniques, geophysics computing, image processing, radar interferometry, remote sensing by radar, synthetic aperture radar, topography (Earth)ENVISAT images, Monte Carlo simulations, SAR interferometry applications, decorrelation models, interferometric phases, line-of-sight displacement, line-of-sight motion, multiimage synthetic aperture radar interferometry, physical parameters, residual topography, target statistics.
    Abstract: This paper focuses on multiimage synthetic aperture radar interferometry (InSAR) in the presence of distributed scatterers, paying particular attention to the role of target decorrelation in the estimation process. This phenomenon is accounted for by splitting the analysis into two steps. In the first step, we estimate the interferometric phases from the data, whereas in the second step, we use these phases to retrieve the physical parameters of interest, such as line-of-sight (LOS) displacement and residual topography. In both steps, we make the hypothesis that target statistics are at least approximately known. This approach is suited both to derive the performances of InSAR with different decorrelation models and for providing an actual estimate of LOS motion and topography. Results achieved from Monte Carlo simulations and a set of repeated pass ENVISAT images are shown.

    @Article{montiGuarnieriTebaldiniTGRS2008,
    author = {Monti-Guarnieri, Andrea and Tebaldini, Stefano},
    title = {On the Exploitation of Target Statistics for SAR Interferometry Applications},
    journal = {IEEE Transactions on Geoscience and Remote Sensing},
    year = {2008},
    volume = {46},
    number = {11},
    pages = {3436-3443},
    month = {nov},
    issn = {0196-2892},
    abstract = {This paper focuses on multiimage synthetic aperture radar interferometry (InSAR) in the presence of distributed scatterers, paying particular attention to the role of target decorrelation in the estimation process. This phenomenon is accounted for by splitting the analysis into two steps. In the first step, we estimate the interferometric phases from the data, whereas in the second step, we use these phases to retrieve the physical parameters of interest, such as line-of-sight (LOS) displacement and residual topography. In both steps, we make the hypothesis that target statistics are at least approximately known. This approach is suited both to derive the performances of InSAR with different decorrelation models and for providing an actual estimate of LOS motion and topography. Results achieved from Monte Carlo simulations and a set of repeated pass ENVISAT images are shown.},
    doi = {10.1109/TGRS.2008.2001756},
    keywords = {SAR Processing, Phase Linking, SAR Tomography, geophysical techniques, geophysics computing, image processing, radar interferometry, remote sensing by radar, synthetic aperture radar, topography (Earth)ENVISAT images, Monte Carlo simulations, SAR interferometry applications, decorrelation models, interferometric phases, line-of-sight displacement, line-of-sight motion, multiimage synthetic aperture radar interferometry, physical parameters, residual topography, target statistics},
    owner = {ofrey},
    pdf = {../../../docs/montiGuarnieriTebaldiniTGRS2008.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4685949&isnumber=4685926},
    
    }
    


  22. Felix Morsdorf, Othmar Frey, Erich Meier, Klaus I. Itten, and Britta Allgöwer. Assessment of the Influence of Flying Altitude and Scan Angle on Biophysical Vegetation Products Derived from Airborne Laser Scanning. International Journal of Remote Sensing, 29(5):1387 - 1406, March 2008.
    Abstract: Airborne Laser Scanning (ALS) has been established as a valuable tool for the estimation of biophysical vegetation properties such as tree height, crown width, fractional cover and leaf area index (LAI). It is expected that the conditions of data acquisition, such as viewing geometry and sensor configuration influence the value of these parameters. In order to gain knowledge about these different conditions, we test for the sensitivity of vegetation products for viewing geometry, namely flying altitude and scanning (incidence) angle. Based on two methodologies for single tree extraction and derivation of fractional cover and LAI previously developed and published by our group, we evaluate how these variables change with either flying altitude or scanning angle. These are the two parameters which often need to be optimized towards the best compromise between point density and area covered with a single flight line, in order to reduce acquisition costs. Our test-site in the Swiss National Park was sampled with two nominal flying altitudes, 500 and 900 m above ground. Incidence angle and local incidence angle were computed based on the digital terrain model using a simple backward geocoding procedure. We divided the raw laser returns into several different incident angle classes based on the flight path data; the TopoSys Falcon II system used in this study has a maximum scan angle of 7.15 deg . We compared the derived biophysical properties from each of these classes with field measurements based on tachymeter measurements and hemispherical photographs, which were geolocated using differential GPS. It was found that with increasing flying height the well-known underestimation of tree height increases. A similar behaviour can be observed for fractional cover; its respective values decrease with higher flying height. The minimum distance between first and last echo increases from 1.2 metres for 500 m AGL to more than 3 metres for 900 m AGL, which does alter return statistics. The behaviour for incidence angles is not so evident, probably due to the small scanning angle of the system used. fCover seems to be most affected by incidence angles, with significantly higher differences for locations further away from nadir. As expected, incidence angle appears to be of higher importance for vegetation density parameters than local incidence angle.

    @Article{morsdorfFreyMeierIttenAllgoewer08:Lidar,
    author = {Felix Morsdorf and Othmar Frey and Erich Meier and Klaus I. Itten and Britta Allg{\"o}wer},
    title = {{Assessment of the Influence of Flying Altitude and Scan Angle on Biophysical Vegetation Products Derived from Airborne Laser Scanning}},
    journal = {International Journal of Remote Sensing},
    year = {2008},
    volume = {29},
    number = {5},
    pages = {1387 -- 1406},
    month = mar,
    abstract = {Airborne Laser Scanning (ALS) has been established as a valuable tool for the estimation of biophysical vegetation properties such as tree height, crown width, fractional cover and leaf area index (LAI). It is expected that the conditions of data acquisition, such as viewing geometry and sensor configuration influence the value of these parameters. In order to gain knowledge about these different conditions, we test for the sensitivity of vegetation products for viewing geometry, namely flying altitude and scanning (incidence) angle. Based on two methodologies for single tree extraction and derivation of fractional cover and LAI previously developed and published by our group, we evaluate how these variables change with either flying altitude or scanning angle. These are the two parameters which often need to be optimized towards the best compromise between point density and area covered with a single flight line, in order to reduce acquisition costs. Our test-site in the Swiss National Park was sampled with two nominal flying altitudes, 500 and 900 m above ground. Incidence angle and local incidence angle were computed based on the digital terrain model using a simple backward geocoding procedure. We divided the raw laser returns into several different incident angle classes based on the flight path data; the TopoSys Falcon II system used in this study has a maximum scan angle of 7.15 deg . We compared the derived biophysical properties from each of these classes with field measurements based on tachymeter measurements and hemispherical photographs, which were geolocated using differential GPS. It was found that with increasing flying height the well-known underestimation of tree height increases. A similar behaviour can be observed for fractional cover; its respective values decrease with higher flying height. The minimum distance between first and last echo increases from 1.2 metres for 500 m AGL to more than 3 metres for 900 m AGL, which does alter return statistics. The behaviour for incidence angles is not so evident, probably due to the small scanning angle of the system used. fCover seems to be most affected by incidence angles, with significantly higher differences for locations further away from nadir. As expected, incidence angle appears to be of higher importance for vegetation density parameters than local incidence angle.},
    doi = {10.1080/01431160701736349},
    file = {:morsdorfFreyMeierIttenAllgoewer08.pdf:PDF},
    pdf = {../../../docs/morsdorfFreyMeierIttenAllgoewer08.pdf},
    url = {http://www.informaworld.com/openurl?genre=article&issn=0143-1161&volume=29&issue=5&spage=1387},
    
    }
    


  23. Maxim Neumann, Laurent Ferro-Famil, and Andreas Reigber. Multibaseline Polarimetric SAR Interferometry Coherence Optimization. IEEE Geosci. Remote Sens. Lett., 5(1):93-97, January 2008. Keyword(s): coherence, optimisation, radar interferometry, radar polarimetry, synthetic aperture radar, coherence optimization, multibaseline polarimetric SAR interferometry, scattering mechanism, synthetic aperture radar sensor, Interferometry, L-band, Optimization methods, Phase estimation, Polarimetric synthetic aperture radar, Polarization, Radar scattering, Samarium, Signal resolution, Uncertainty, Coherence optimization, multibaseline (MB), polarimetric synthetic aperture radar interferometry (PolInSAR).
    Abstract: This letter analyzes different approaches for polarimetric optimization of multibaseline (MB) interferometric coherences. Two general methods are developed to simultaneously optimize coherences for more than two data sets. The first method provides every data set with a distinct dominant scattering mechanism (SM). The second optimization method is constrained to use equal SMs at all data sets. As the experimental results indicate, MB coherence optimization does improve the accuracy in the estimation of dominant SMs and the associated interferometric phases. Both methods are evaluated on real data acquired by the German Aerospace Agency (DLR)'s enhanced synthetic aperture radar sensor (ESAR) at L-band.

    @Article{neumannFerroFamilReigberGRSL2008MBPolInterferoCoherenceOptimization,
    author = {Maxim Neumann and Laurent Ferro-Famil and Andreas Reigber},
    title = {Multibaseline Polarimetric {SAR} Interferometry Coherence Optimization},
    journal = {IEEE Geosci. Remote Sens. Lett.},
    year = {2008},
    volume = {5},
    number = {1},
    pages = {93-97},
    month = jan,
    issn = {1545-598X},
    abstract = {This letter analyzes different approaches for polarimetric optimization of multibaseline (MB) interferometric coherences. Two general methods are developed to simultaneously optimize coherences for more than two data sets. The first method provides every data set with a distinct dominant scattering mechanism (SM). The second optimization method is constrained to use equal SMs at all data sets. As the experimental results indicate, MB coherence optimization does improve the accuracy in the estimation of dominant SMs and the associated interferometric phases. Both methods are evaluated on real data acquired by the German Aerospace Agency (DLR)'s enhanced synthetic aperture radar sensor (ESAR) at L-band.},
    doi = {10.1109/LGRS.2007.908885},
    keywords = {coherence;optimisation;radar interferometry;radar polarimetry;synthetic aperture radar;coherence optimization;multibaseline polarimetric SAR interferometry;scattering mechanism;synthetic aperture radar sensor;Interferometry;L-band;Optimization methods;Phase estimation;Polarimetric synthetic aperture radar;Polarization;Radar scattering;Samarium;Signal resolution;Uncertainty;Coherence optimization;multibaseline (MB);polarimetric synthetic aperture radar interferometry (PolInSAR)},
    owner = {ofrey},
    
    }
    


  24. Matteo Pardini, Fabrizio Lombardini, and Fabrizio Gini. The Hybrid Cramér -- Rao Bound on Broadside DOA Estimation of Extended Sources in Presence of Array Errors. IEEE Transactions on Signal Processing, 56(4):1726-1730, April 2008. Keyword(s): SAR Processing, SAR Tomography, Tomography, Residual Motion Errors, InSAR, SAR Interferometry, Interferometry, antenna arrays, direction-of-arrival estimation, DOA estimation, hybrid Cramer-Rao bound, multibaseline interferometers, randomly perturbed arrays, remote sensing systems, signal direction of arrival, synthetic aperture radar.
    Abstract: In this correspondence we derive explicit expressions for the hybrid Cramer-Rao lower bound (HCRB) on the estimation accuracy of signal direction of arrival (DOA) from data collected by randomly perturbed arrays. The presence of a wavefront spatial decorrelation, which is modeled as a multiplicative correlated noise, has also been taken into account in the data model, since it is typical in those applications involving extended sources. In particular, we consider perturbations in sensor positions. Existing approaches to DOA HCRB calculation do not consider the presence of multiplicative noise and are referred to the assumption of small perturbations only, still not being worked out explicitly. Here, we assume that the impinging wavefronts are coming from broadside or more generally from a narrow DOA sector, allowing the explicit derivation of the HCRB for any variance of the sensor positioning errors in the line-of-sight direction. This scenario corresponds to the typical operative condition of remote sensing systems such as synthetic aperture radar (SAR) multibaseline interferometers, for which a few HCRB sample curves are reported.

    @Article{pardiniLombardiniGini2008:Tomo,
    Title = {{The Hybrid Cram{\'e}r -- Rao Bound on Broadside DOA Estimation of Extended Sources in Presence of Array Errors}},
    Author = {Pardini, Matteo and Lombardini, Fabrizio and Gini, Fabrizio},
    Doi = {10.1109/TSP.2007.910540},
    ISSN = {1053-587X},
    Month = {apr},
    Number = {4},
    Pages = {1726-1730},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4471888&isnumber=4471869},
    Volume = {56},
    Year = {2008},
    Abstract = {In this correspondence we derive explicit expressions for the hybrid Cramer-Rao lower bound (HCRB) on the estimation accuracy of signal direction of arrival (DOA) from data collected by randomly perturbed arrays. The presence of a wavefront spatial decorrelation, which is modeled as a multiplicative correlated noise, has also been taken into account in the data model, since it is typical in those applications involving extended sources. In particular, we consider perturbations in sensor positions. Existing approaches to DOA HCRB calculation do not consider the presence of multiplicative noise and are referred to the assumption of small perturbations only, still not being worked out explicitly. Here, we assume that the impinging wavefronts are coming from broadside or more generally from a narrow DOA sector, allowing the explicit derivation of the HCRB for any variance of the sensor positioning errors in the line-of-sight direction. This scenario corresponds to the typical operative condition of remote sensing systems such as synthetic aperture radar (SAR) multibaseline interferometers, for which a few HCRB sample curves are reported.},
    Journal = {IEEE Transactions on Signal Processing},
    Keywords = {SAR Processing, SAR Tomography, Tomography, Residual Motion Errors, InSAR, SAR Interferometry, Interferometry, antenna arrays, direction-of-arrival estimation, DOA estimation, hybrid Cramer-Rao bound, multibaseline interferometers, randomly perturbed arrays, remote sensing systems, signal direction of arrival, synthetic aperture radar},
    Owner = {ofrey},
    Pdf = {../../../docs/pardiniLombardiniGini2008.pdf} 
    }
    


  25. Daniele Perissin. Validation of the Submetric Accuracy of Vertical Positioning of PSs in C-Band. IEEE Geosci. Remote Sens. Lett., 5(3):502-506, July 2008. Keyword(s): SAR Processing, Persistent Scatterer Interferometry, PSI, SAR Interferometry, InSAR, DInSAR, Interferometry, digital elevation models, geophysical signal processing, photogrammetry, radar interferometry, remote sensing by radar, synthetic aperture radar, terrain mapping, C-band, DEM, Envisat images, European Remote Sensing satellite, European Space Agency, Italy, Milan, Shuttle Radar Topography Mission, digital elevation models, digital terrain models, height estimate, multitrack PS DTM, permanent scatterers technique, photogrammetric technique, radar target displacement, spaceborne synthetic aperture radar interferometry, street level, submetric accuracy, target localization capability, urban area, vertical positioning, Interferometry, remote sensing, synthetic aperture radar (SAR);.
    Abstract: The permanent scatterers (PSs) technique is an operational tool in the context of spaceborne synthetic aperture radar interferometry for monitoring the displacement of radar targets with millimetric accuracy. Recently, the target localization capability of the PS technique has been subject of study, and the possibility of generating digital elevation models (DEMs) and digital terrain models (DTMs) by means of the height of a sparse set of points has been evaluated. In this letter, for the first time, the PS height estimate has been validated by exploiting about 250,000 spot heights at street level derived from photogrammetric techniques in the urban area around Milan, Italy. The very high correlation between the two independent measurements confirms the theoretical submetric accuracy of vertical positioning. A multitrack PS DTM has then been generated and compared to the spot heights together with the corresponding Shuttle Radar Topography Mission (SRTM) DEM, showing the very high improvement given by the PS technique to the freely available topographic data. The results have been obtained by processing about 300 European Space Agency (ESA) European Remote Sensing (ERS) satellite and Envisat images acquired from two descending tracks and an ascending one over Milan.

    @Article{perissinGRSL2008PSI,
    author = {Perissin, Daniele},
    title = {Validation of the Submetric Accuracy of Vertical Positioning of {PSs} in {C}-Band},
    journal = {IEEE Geosci. Remote Sens. Lett.},
    year = {2008},
    volume = {5},
    number = {3},
    pages = {502-506},
    month = jul,
    issn = {1545-598X},
    abstract = {The permanent scatterers (PSs) technique is an operational tool in the context of spaceborne synthetic aperture radar interferometry for monitoring the displacement of radar targets with millimetric accuracy. Recently, the target localization capability of the PS technique has been subject of study, and the possibility of generating digital elevation models (DEMs) and digital terrain models (DTMs) by means of the height of a sparse set of points has been evaluated. In this letter, for the first time, the PS height estimate has been validated by exploiting about 250,000 spot heights at street level derived from photogrammetric techniques in the urban area around Milan, Italy. The very high correlation between the two independent measurements confirms the theoretical submetric accuracy of vertical positioning. A multitrack PS DTM has then been generated and compared to the spot heights together with the corresponding Shuttle Radar Topography Mission (SRTM) DEM, showing the very high improvement given by the PS technique to the freely available topographic data. The results have been obtained by processing about 300 European Space Agency (ESA) European Remote Sensing (ERS) satellite and Envisat images acquired from two descending tracks and an ascending one over Milan.},
    doi = {10.1109/LGRS.2008.921210},
    file = {:perissinGRSL2008PSI.pdf:PDF},
    keywords = {SAR Processing, Persistent Scatterer Interferometry, PSI, SAR Interferometry, InSAR, DInSAR, Interferometry, digital elevation models;geophysical signal processing;photogrammetry;radar interferometry;remote sensing by radar;synthetic aperture radar;terrain mapping;C-band;DEM;Envisat images;European Remote Sensing satellite;European Space Agency;Italy;Milan;Shuttle Radar Topography Mission;digital elevation models;digital terrain models;height estimate;multitrack PS DTM;permanent scatterers technique;photogrammetric technique;radar target displacement;spaceborne synthetic aperture radar interferometry;street level;submetric accuracy;target localization capability;urban area;vertical positioning;Interferometry;remote sensing;synthetic aperture radar (SAR);},
    pdf = {../../../docs/perissinGRSL2008PSI.pdf},
    
    }
    


  26. S. Perna, C. Wimmer, J. Moreira, and G. Fornaro. X-Band Airborne Differential Interferometry: Results of the OrbiSAR Campaign Over the Perugia Area. IEEE Trans. Geosci. Remote Sens., 46(2):489-503, February 2008. Keyword(s): SAR Processing, BFNT, Backward-Forward to the Nominale Track, Airborne SAR, D-InSAR, differential SAR interferometry, Interferometry, OrbiSAR, X-Band, Motion Compensation, Residual Motion Errors, Autofocus, Airborne SAR, airborne radar, motion compensation, radar imaging, synthetic aperture radar airborne SAR images, digital elevation model inaccuracies, motion compensation errors, phase errors.
    Abstract: Differential synthetic aperture radar interferometry (DInSAR) is a remote sensing technique that allows monitoring ground deformation with accuracy of the order of fractions of the radiated wavelength, by means of proper combination and processing of repeat-pass data. In contrast to the satellite case, application of such a technique to airborne data is not, today, a well-established task. Several airborne campaigns, involving mainly C/L-band data, have been planned in the last years to exploit the potentialities of these more flexible platforms for deformation monitoring. In this paper, we show the results of an airborne DInSAR X-band experiment carried out over the Perugia area (center of Italy) by using the OrbiSAR system. We discuss the processing chain applied to the acquired data, which allows achieving a satisfactory compromise between accuracy and efficiency. Eleven repeated passes were carried out in two days; two corner reflectors were located on the ground in a hilly region. One corner reflector was vertically moved between the two days to evaluate the system detection capability. Moreover, we carry out an analysis of all possible differential interferograms for a region 2 x 4 km wide.

    @Article{pernaWimmerMoreiraFornaro2008AirborneDInSARXBand,
    author = {Perna, S. and Wimmer, C. and Moreira, J. and Fornaro, G.},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    title = {X-Band Airborne Differential Interferometry: Results of the {OrbiSAR} Campaign Over the {Perugia} Area},
    year = {2008},
    issn = {0196-2892},
    month = feb,
    number = {2},
    pages = {489-503},
    volume = {46},
    abstract = {Differential synthetic aperture radar interferometry (DInSAR) is a remote sensing technique that allows monitoring ground deformation with accuracy of the order of fractions of the radiated wavelength, by means of proper combination and processing of repeat-pass data. In contrast to the satellite case, application of such a technique to airborne data is not, today, a well-established task. Several airborne campaigns, involving mainly C/L-band data, have been planned in the last years to exploit the potentialities of these more flexible platforms for deformation monitoring. In this paper, we show the results of an airborne DInSAR X-band experiment carried out over the Perugia area (center of Italy) by using the OrbiSAR system. We discuss the processing chain applied to the acquired data, which allows achieving a satisfactory compromise between accuracy and efficiency. Eleven repeated passes were carried out in two days; two corner reflectors were located on the ground in a hilly region. One corner reflector was vertically moved between the two days to evaluate the system detection capability. Moreover, we carry out an analysis of all possible differential interferograms for a region 2 x 4 km wide.},
    doi = {10.1109/TGRS.2007.908871},
    file = {:pernaWimmerMoreiraFornaro2008AirborneDInSARXBand.pdf:PDF},
    keywords = {SAR Processing, BFNT, Backward-Forward to the Nominale Track, Airborne SAR, D-InSAR, differential SAR interferometry, Interferometry, OrbiSAR, X-Band, Motion Compensation, Residual Motion Errors, Autofocus, Airborne SAR, airborne radar, motion compensation, radar imaging, synthetic aperture radar airborne SAR images, digital elevation model inaccuracies, motion compensation errors, phase errors},
    pdf = {../../../docs/pernaWimmerMoreiraFornaro2008.pdf},
    url = {http://www.ieeexplore.ieee.org/iel5/36/4432701/04432715.pdf},
    
    }
    


  27. L. Pipia, X. Fabregas, A. Aguasca, and C. Lopez-Martinez. Atmospheric Artifact Compensation in Ground-Based DInSAR Applications. IEEE Geosci. Remote Sens. Lett., 5(1):88-92, January 2008. Keyword(s): GB-SAR, ground-based SAR, terrestrial SAR, atmospheric humidity, atmospheric pressure, atmospheric techniques, atmospheric temperature, radar interferometry, synthetic aperture radar, AD 2005 06, Barcelona, Collserola Park, Spain, Universitat Politecnica de Catalunya, atmosphere variations, atmospheric artifact compensation, atmospheric humidity, atmospheric pressure, atmospheric temperature, coherence-based technique, differential interferometry Synthetic Aperture Radar, ground-Based DInSAR applications, heterogeneous environment, interferometric information, polarimetric measurements, Atmosphere, Atmospheric measurements, Atmospheric modeling, Information retrieval, Interferometry, Layout, Sensor phenomena and characterization, Sensor systems, Synthetic aperture radar, Testing, Differential interferometric SAR (DInSAR), GB-SAR sensor, polarimetric SAR (PolSAR), synthetic aperture radar (SAR).
    @Article{pipiaFabregasAguascaLopezMartinezGRSL2008APSCompensationInGBDInSAR,
    author = {L. Pipia and X. Fabregas and A. Aguasca and C. Lopez-Martinez},
    journal = {IEEE Geosci. Remote Sens. Lett.},
    title = {Atmospheric Artifact Compensation in Ground-Based {DInSAR} Applications},
    year = {2008},
    issn = {1545-598X},
    month = jan,
    number = {1},
    pages = {88--92},
    volume = {5},
    doi = {10.1109/LGRS.2007.908364},
    file = {:pipiaFabregasAguascaLopezMartinezGRSL2008APSCompensationInGBDInSAR.pdf:PDF},
    keywords = {GB-SAR,ground-based SAR, terrestrial SAR,atmospheric humidity, atmospheric pressure, atmospheric techniques, atmospheric temperature, radar interferometry, synthetic aperture radar, AD 2005 06, Barcelona, Collserola Park, Spain, Universitat Politecnica de Catalunya, atmosphere variations, atmospheric artifact compensation, atmospheric humidity, atmospheric pressure, atmospheric temperature, coherence-based technique, differential interferometry Synthetic Aperture Radar, ground-Based DInSAR applications, heterogeneous environment, interferometric information, polarimetric measurements, Atmosphere, Atmospheric measurements, Atmospheric modeling, Information retrieval, Interferometry, Layout, Sensor phenomena and characterization, Sensor systems, Synthetic aperture radar, Testing, Differential interferometric SAR (DInSAR), GB-SAR sensor, polarimetric SAR (PolSAR), synthetic aperture radar (SAR)},
    owner = {ofrey},
    
    }
    


  28. Pau Prats, J. J. Mallorqui, Andreas Reigber, Rolf Scheiber, and Alberto Moreira. Estimation of the Temporal Evolution of the Deformation Using Airborne Differential SAR Interferometry. IEEE Transactions on Geoscience and Remote Sensing, 46(4):1065-1078, April 2008. Keyword(s): SAR Processing, DInSAR, InSAR, Interferometry, digital elevation models, error analysis, motion compensation, MoComp, radar interferometry, Multi-Baseline SAR, synthetic aperture radar, topography (Earth)DLR, Experimental SAR system, E-SAR, Airborne SAR, German Aerospace Center, agricultural fields, airborne differential synthetic aperture radar interferometry, baseline error, corner reflector, deformation, differential interferometry processor, digital elevation model, image coregistration, residual motion errors, temporal evolution, topography.
    Abstract: This paper presents airborne differential synthetic aperture radar (SAR) interferometry results using a stack of 14 images, which were acquired by the Experimental SAR system of the German Aerospace Center (DLR) during a time span of 2.5 h. An advanced differential technique is used to retrieve the error in the digital elevation model and the temporal evolution of the deformation for every coherent pixel in the image. The two main limitations in airborne SAR processing are analyzed, namely, the existence of residual motion errors (RMEs) (inaccuracies in the navigation system on the order of 1-5 cm) and the accommodation of the topography and the aperture dependence on motion errors during the processing. The coupling between them is also addressed, showing that the estimation of the differential RME, i.e., baseline error, can be biased when using techniques based on the coregistration between interferometric looks. The SAR focusing chain to process the data is also presented together with the modifications in the differential interferometry processor to deal with the remaining baseline error. The detected motion of a corner reflector and the measured deformation in several agricultural fields allows one to validate the proposed techniques.

    @Article{pratsReigberMallorquiScheiberMoreira2008:DInSAR,
    Title = {{Estimation of the Temporal Evolution of the Deformation Using Airborne Differential SAR Interferometry}},
    Author = {Prats, Pau and Mallorqui, J. J. and Reigber, Andreas and Scheiber, Rolf and Moreira, Alberto},
    ISSN = {0196-2892},
    Month = {apr},
    Number = {4},
    Pages = {1065-1078},
    Url = {http://ieeexplore.ieee.org/iel5/36/4475343/04464121.pdf},
    Volume = {46},
    Year = {2008},
    Abstract = {This paper presents airborne differential synthetic aperture radar (SAR) interferometry results using a stack of 14 images, which were acquired by the Experimental SAR system of the German Aerospace Center (DLR) during a time span of 2.5 h. An advanced differential technique is used to retrieve the error in the digital elevation model and the temporal evolution of the deformation for every coherent pixel in the image. The two main limitations in airborne SAR processing are analyzed, namely, the existence of residual motion errors (RMEs) (inaccuracies in the navigation system on the order of 1-5 cm) and the accommodation of the topography and the aperture dependence on motion errors during the processing. The coupling between them is also addressed, showing that the estimation of the differential RME, i.e., baseline error, can be biased when using techniques based on the coregistration between interferometric looks. The SAR focusing chain to process the data is also presented together with the modifications in the differential interferometry processor to deal with the remaining baseline error. The detected motion of a corner reflector and the measured deformation in several agricultural fields allows one to validate the proposed techniques.},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, DInSAR, InSAR, Interferometry, digital elevation models, error analysis, motion compensation, MoComp, radar interferometry, Multi-Baseline SAR, synthetic aperture radar, topography (Earth)DLR, Experimental SAR system, E-SAR, Airborne SAR, German Aerospace Center, agricultural fields, airborne differential synthetic aperture radar interferometry, baseline error, corner reflector, deformation, differential interferometry processor, digital elevation model, image coregistration, residual motion errors, temporal evolution, topography},
    Owner = {ofrey},
    Pdf = {../../../docs/pratsReigberMallorquiScheiberMoreira2008.pdf} 
    }
    


  29. Xiaolan Qiu, Donghui Hu, and Chibiao Ding. An Improved NLCS Algorithm With Capability Analysis for One-Stationary BiSAR. IEEE Trans. Geosci. Remote Sens., 46(10):3179-3186, Oct. 2008. Keyword(s): geophysical techniques, synthetic aperture radarBiSAR imaging problem, NLCS algorithm, azimuth perturbation, compensation methods, differential range cell migration correction, local fit method, nonlinear chirp scaling algorithm, one-stationary bistatic SAR, range chirp scaling function.
    Abstract: This paper deals with the imaging problem of one-stationary bistatic SAR (BiSAR) with large bistatic angle. An improved nonlinear chirp scaling (NLCS) algorithm is proposed for this BiSAR. The main work here includes three aspects. First, a range chirp scaling function for correcting the differential range cell migration correction is derived. Then, the azimuth perturbation is generated by local fit method, which makes the NLCS algorithm suitable for the large bistatic angle case. Furthermore, the negative effects introduced by the perturbation (including phase error and locality error) are discussed, and some compensation methods are proposed to enhance the capability of the algorithm. The simulating results exhibited at the end of this paper validate the correctness of the analysis and the feasibility of the algorithm.

    @Article{QiuHuDing2008:NLCS,
    author = {Xiaolan Qiu and Donghui Hu and Chibiao Ding},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    title = {An Improved NLCS Algorithm With Capability Analysis for One-Stationary BiSAR},
    year = {2008},
    issn = {0196-2892},
    month = {Oct.},
    number = {10},
    pages = {3179-3186},
    volume = {46},
    abstract = {This paper deals with the imaging problem of one-stationary bistatic SAR (BiSAR) with large bistatic angle. An improved nonlinear chirp scaling (NLCS) algorithm is proposed for this BiSAR. The main work here includes three aspects. First, a range chirp scaling function for correcting the differential range cell migration correction is derived. Then, the azimuth perturbation is generated by local fit method, which makes the NLCS algorithm suitable for the large bistatic angle case. Furthermore, the negative effects introduced by the perturbation (including phase error and locality error) are discussed, and some compensation methods are proposed to enhance the capability of the algorithm. The simulating results exhibited at the end of this paper validate the correctness of the analysis and the feasibility of the algorithm.},
    doi = {10.1109/TGRS.2008.921569},
    keywords = {geophysical techniques, synthetic aperture radarBiSAR imaging problem, NLCS algorithm, azimuth perturbation, compensation methods, differential range cell migration correction, local fit method, nonlinear chirp scaling algorithm, one-stationary bistatic SAR, range chirp scaling function},
    
    }
    


  30. Eric J. Rignot, Jonathan L. Bamber, Michiel R. van den Broeke, Curt Davis, Yonghong Li, Willem Jan van de Berg, and Erik van Meijgaard. Recent Antarctic ice mass loss from radar interferometry and regional climate modelling. Nature Geosci, 1(2):106-110, February 2008.
    @Article{rignotBamberVanDenBroekeDavisLiVanDeBergVanMeijgaardNatureGeoscience2008AntarcticIceMassLoss,
    author = {Rignot, Eric J. and Bamber, Jonathan L. and van den Broeke, Michiel R. and Davis, Curt and Li, Yonghong and van de Berg, Willem Jan and van Meijgaard, Erik},
    title = {Recent Antarctic ice mass loss from radar interferometry and regional climate modelling},
    journal = {Nature Geosci},
    year = {2008},
    volume = {1},
    number = {2},
    pages = {106--110},
    month = feb,
    issn = {1752-0894},
    comment = {10.1038/ngeo102},
    file = {:rignotBamberVanDenBroekeDavisLiVanDeBergVanMeijgaardNatureGeoscience2008AntarcticIceMassLoss.pdf:PDF},
    owner = {ofrey},
    pdf = {../../../docs/rignotBamberVanDenBroekeDavisLiVanDeBergVanMeijgaardNatureGeoscience2008AntarcticIceMassLoss.pdf},
    publisher = {Nature Publishing Group},
    url = {http://dx.doi.org/10.1038/ngeo102},
    
    }
    


  31. Christian Ruckstuhl, Rolf Philipona, Klaus Behrens, Martine Collaud Coen, Bruno Dürr, Alain Heimo, Christian Mätzler, Stephan Nyeki, Atsumu Ohmura, Laurent Vuilleumier, and others. Aerosol and cloud effects on solar brightening and the recent rapid warming. Geophysical Research Letters, 35(12), 2008.
    @Article{Ruckstuhl2008,
    author = {Ruckstuhl, Christian and Philipona, Rolf and Behrens, Klaus and Collaud Coen, Martine and D{\"u}rr, Bruno and Heimo, Alain and M{\"a}tzler, Christian and Nyeki, Stephan and Ohmura, Atsumu and Vuilleumier, Laurent and others},
    title = {Aerosol and cloud effects on solar brightening and the recent rapid warming},
    journal = {Geophysical Research Letters},
    year = {2008},
    volume = {35},
    number = {12},
    owner = {ofrey},
    publisher = {Wiley Online Library},
    
    }
    


  32. T.K. Sjogren, V.T. Vu, and M.I. Pettersson. A comparative study of the polar version with the subimage version of Fast Factorized Backprojection in UWB SAR. International Radar Symposium, pp 1-4, May 2008. Keyword(s): SAR Processing, Time-Domain Back-Projection, TDBP, Fast Back-Projection, Back-Projection, Fast Factorized Back-Projection, Comparison of Algorithms, interpolation, radar imaging, synthetic aperture radar, time-domain analysis, ultra wideband radar, UWB SAR, interpolation method, phase error, polar version, subimage version, time domain SAR algorithm, Factorized Back-Projection.
    Abstract: This paper presents a comparative study of the polar and the subimage based variants of the time domain SAR algorithm Fast Factorized Backprojection. The difference between the two variants with regard to the phase error, which causes defocusing in the image, is investigated. The difference between the algorithms in interpolation between stages is also discussed. To investigate the sidelobes in azimuth, the paper gives simulation results for a low frequency UWB SAR system for both algorithms. How the algorithms differ with regard to amount of beams and length of beams is also discussed.

    @Article{sjoerenVuPetterson2008:FFBPComparison,
    Title = {{A comparative study of the polar version with the subimage version of Fast Factorized Backprojection in UWB SAR}},
    Author = {Sjogren, T.K. and Vu, V.T. and Pettersson, M.I.},
    Doi = {10.1109/IRS.2008.4585740},
    Month = {May},
    Pages = {1-4},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4585740&isnumber=4585695},
    Year = {2008},
    Abstract = {This paper presents a comparative study of the polar and the subimage based variants of the time domain SAR algorithm Fast Factorized Backprojection. The difference between the two variants with regard to the phase error, which causes defocusing in the image, is investigated. The difference between the algorithms in interpolation between stages is also discussed. To investigate the sidelobes in azimuth, the paper gives simulation results for a low frequency UWB SAR system for both algorithms. How the algorithms differ with regard to amount of beams and length of beams is also discussed.},
    Journal = {International Radar Symposium},
    Keywords = {SAR Processing, Time-Domain Back-Projection, TDBP, Fast Back-Projection, Back-Projection, Fast Factorized Back-Projection, Comparison of Algorithms, interpolation, radar imaging, synthetic aperture radar, time-domain analysis, ultra wideband radar, UWB SAR, interpolation method, phase error, polar version, subimage version, time domain SAR algorithm,Factorized Back-Projection},
    Owner = {ofrey},
    Pdf = {../../../docs/sjoerenVuPetterson2008.pdf} 
    }
    


  33. Robert Wang, Otmar Loffeld, Qurat Ul-Ann, Holger Nies, Amaya Medrano Ortiz, and Ashraf Samarah. A Bistatic Point Target Reference Spectrum for General Bistatic SAR Processing. IEEE Trans. Geosci. Remote Sens.L, 5(3):517-521, July 2008. Keyword(s): SAR Processing, Bistatic SAR, Loffeld bistatic formula, airborne configuration, azimuth time-bandwidth products, bistatic point target reference spectrum, bistatic synthetic aperture radar, general bistatic SAR processing, spaceborne configuration, total azimuth modulation, total azimuth phase, geophysical signal processing, radar signal processing, synthetic aperture radar.
    Abstract: A bistatic point target reference spectrum (BPTRS) based on Loffeld's bistatic formula (LBF) is derived in this letter. For LBF, the same contributions of the transmitter and receiver to the total azimuth modulation are assumed. This assumption results in the failure of LBF in the extreme configuration (i.e., spaceborne/airborne configuration). For general bistatic configurations, the azimuth modulations are unequal for the transmitter and receiver due to the different slant ranges and velocities. Therefore, the azimuth time-bandwidth products (TBPs) from the transmitter and receiver are different; in some cases (e.g., spaceborne/airborne case), one of them might be very small, which might even result in a serious error of the principle of stationary phase. This letter uses TBP to weight the azimuth phase modulation contributions of the transmitter and receiver to the common azimuth spectrum to approximately obtain the point of stationary phase of the total azimuth phase history. Simulations show that the proposed BPTRS can work well for spaceborne/airborne configurations.

    @Article{WangLoffeldUlAnnNiesOrtizSamarah2008:Bistatic,
    author = {Wang, Robert and Loffeld, Otmar and Ul-Ann, Qurat and Nies, Holger and Ortiz, Amaya Medrano and Samarah, Ashraf},
    journal = {IEEE Trans. Geosci. Remote Sens.} # L,
    title = {A Bistatic Point Target Reference Spectrum for General Bistatic {SAR} Processing},
    year = {2008},
    issn = {1545-598X},
    month = jul,
    number = {3},
    pages = {517-521},
    volume = {5},
    abstract = {A bistatic point target reference spectrum (BPTRS) based on Loffeld's bistatic formula (LBF) is derived in this letter. For LBF, the same contributions of the transmitter and receiver to the total azimuth modulation are assumed. This assumption results in the failure of LBF in the extreme configuration (i.e., spaceborne/airborne configuration). For general bistatic configurations, the azimuth modulations are unequal for the transmitter and receiver due to the different slant ranges and velocities. Therefore, the azimuth time-bandwidth products (TBPs) from the transmitter and receiver are different; in some cases (e.g., spaceborne/airborne case), one of them might be very small, which might even result in a serious error of the principle of stationary phase. This letter uses TBP to weight the azimuth phase modulation contributions of the transmitter and receiver to the common azimuth spectrum to approximately obtain the point of stationary phase of the total azimuth phase history. Simulations show that the proposed BPTRS can work well for spaceborne/airborne configurations.},
    doi = {10.1109/LGRS.2008.923542},
    keywords = {SAR Processing,Bistatic SAR,Loffeld bistatic formula;airborne configuration;azimuth time-bandwidth products;bistatic point target reference spectrum;bistatic synthetic aperture radar;general bistatic SAR processing;spaceborne configuration;total azimuth modulation;total azimuth phase;geophysical signal processing;radar signal processing;synthetic aperture radar},
    
    }
    


  34. Evan C. Zaugg and David G. Long. Theory and Application of Motion Compensation for LFM-CW SAR. IEEE Transactions on Geoscience and Remote Sensing, 46(10):2990-2998, Oct. 2008. Keyword(s): SAR Processing, LFM-CW, LFM-CW SAR, FMCW, MoComp, motion compensation, CSA, ECS, Chirp Scaling, Extended Chirp Scaling, FSA, Frequency Scaling Algorithm, Range-Doppler Algorithm, synthetic aperture radar, Brigham Young University, muSAR system, LFM-CW signal model, SAR image quality, aircraft, atmospheric turbulence, high-resolution synthetic aperture radar systems, linear frequency-modulated continuous-wave signal, motion compensation, motion correction algorithms, unmanned aerial vehicle, Airborne SAR, geophysical techniques.
    Abstract: Small low-cost high-resolution synthetic aperture radar (SAR) systems are made possible by using a linear frequency-modulated continuous-wave (LFM-CW) signal. SAR processing assumes that the sensor is moving in a straight line at a constant speed, but in actuality, an unmanned aerial vehicle (UAV) or airplane will often significantly deviate from this ideal. This nonideal motion can seriously degrade the SAR image quality. In a continuous-wave system, this motion happens during the radar pulse, which means that existing motion compensation techniques that approximate the position as constant over a pulse are limited for LFM-CW SAR. Small aircraft and UAVs are particularly susceptible to atmospheric turbulence, making the need for motion compensation even greater for SARs operating on these platforms. In this paper, the LFM-CW SAR signal model is presented, and processing algorithms are discussed. The effects of nonideal motion on the SAR signal are derived, and new methods for motion correction are developed, which correct for motion during the pulse. These new motion correction algorithms are verified with simulated data and with actual data collected using the Brigham Young University muSAR system.

    @Article{zauggLongTGRS2008:MocompLFMCWSAR,
    author = {Zaugg, Evan C. and Long, David G.},
    journal = {IEEE Transactions on Geoscience and Remote Sensing},
    title = {{Theory and Application of Motion Compensation for LFM-CW SAR}},
    year = {2008},
    issn = {0196-2892},
    month = {Oct.},
    number = {10},
    pages = {2990-2998},
    volume = {46},
    abstract = {Small low-cost high-resolution synthetic aperture radar (SAR) systems are made possible by using a linear frequency-modulated continuous-wave (LFM-CW) signal. SAR processing assumes that the sensor is moving in a straight line at a constant speed, but in actuality, an unmanned aerial vehicle (UAV) or airplane will often significantly deviate from this ideal. This nonideal motion can seriously degrade the SAR image quality. In a continuous-wave system, this motion happens during the radar pulse, which means that existing motion compensation techniques that approximate the position as constant over a pulse are limited for LFM-CW SAR. Small aircraft and UAVs are particularly susceptible to atmospheric turbulence, making the need for motion compensation even greater for SARs operating on these platforms. In this paper, the LFM-CW SAR signal model is presented, and processing algorithms are discussed. The effects of nonideal motion on the SAR signal are derived, and new methods for motion correction are developed, which correct for motion during the pulse. These new motion correction algorithms are verified with simulated data and with actual data collected using the Brigham Young University muSAR system.},
    doi = {10.1109/TGRS.2008.921958},
    keywords = {SAR Processing, LFM-CW, LFM-CW SAR, FMCW, MoComp, motion compensation, CSA, ECS, Chirp Scaling, Extended Chirp Scaling, FSA, Frequency Scaling Algorithm, Range-Doppler Algorithm, synthetic aperture radar, Brigham Young University, muSAR system, LFM-CW signal model, SAR image quality, aircraft, atmospheric turbulence, high-resolution synthetic aperture radar systems, linear frequency-modulated continuous-wave signal, motion compensation, motion correction algorithms, unmanned aerial vehicle, Airborne SAR, geophysical techniques},
    pdf = {../../../docs/zauggLongTGRS2008.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4637982&isnumber=4637826},
    
    }
    


Conference articles

  1. Marcelo Albuquerque, Pau Prats, and Rolf Scheiber. Applications of Time-Domain Back-Projection SAR Processing in the Airborne Case. In European Conference on Synthetic Aperture Radar (EUSAR), pages 4, June 2008. VDE Verlag GmbH. Keyword(s): SAR Processsing, Time-Domain Back-Projection, TDBP, Back-Projection, Synthetic Aperture Radar (SAR), motion compensation, tomography, Airborne SAR, E-SAR, Topography-dependent motion compensation, Motion Compensation, MoComp, Interferometry, Non-Linear SAR, Non-Linear Flight Tracks.
    Abstract: The Back-Projection Algorithm is a SAR processing approach that uses time-domain convolution of the SAR data in order to perform SAR focusing. Some benefits of this approach are exact inversion, ideal motion compensation including topography information and handling of general aperture geometries. The implementation of the Back-Projection Algorithm was done focusing on the parallelization aspects. Applications of the algorithm are presented with respect to topography adaptive processing, direct generation of map projections and consideration of non linear trajectories.

    @InProceedings{albuquerquePratsScheiberEUSAR08:TDBP,
    Title = {Applications of Time-Domain Back-Projection SAR Processing in the Airborne Case},
    Author = {Albuquerque, Marcelo and Prats, Pau and Scheiber, Rolf},
    Booktitle = {European Conference on Synthetic Aperture Radar (EUSAR)},
    ISBN = {978-3-8007-3084-1},
    Location = {Friedrichshafen, Germany},
    Month = Jun,
    Pages = {4},
    Publisher = {VDE Verlag GmbH},
    Url = {http://elib.dlr.de/53756/01/albuquerque_EUSAR2008_time_domain.pdf},
    Year = {2008},
    Abstract = {The Back-Projection Algorithm is a SAR processing approach that uses time-domain convolution of the SAR data in order to perform SAR focusing. Some benefits of this approach are exact inversion, ideal motion compensation including topography information and handling of general aperture geometries. The implementation of the Back-Projection Algorithm was done focusing on the parallelization aspects. Applications of the algorithm are presented with respect to topography adaptive processing, direct generation of map projections and consideration of non linear trajectories.},
    Journal = {Proceedings of the European Conference on Synthetic Aperture Radar (EUSAR)},
    Keywords = {SAR Processsing, Time-Domain Back-Projection, TDBP, Back-Projection, Synthetic Aperture Radar (SAR), motion compensation, tomography, Airborne SAR, E-SAR,Topography-dependent motion compensation, Motion Compensation, MoComp, Interferometry, Non-Linear SAR, Non-Linear Flight Tracks},
    Owner = {ofrey},
    Pdf = {../../../docs/albuquerquePratsScheiberEUSAR08.pdf} 
    }
    


  2. Michael Brandfass and Luis Fernando Lobianco. Modified Fast Factorized Backprojection as Applied to X-Band Data for Curved Flight Paths. In European Conference on Synthetic Aperture Radar (EUSAR), pages 4, June 2008. VDE Verlag GmbH. Keyword(s): SAR Processsing, Time-Domain Back-Projection, TDBP, Back-Projection, Fast Factorized Back-Projection, FFBP, Fast Back-Projection, Synthetic Aperture Radar (SAR), motion compensation, tomography, Airborne SAR, X-Band, Motion Compensation, MoComp, Non-Linear SAR, Non-Linear Flight Tracks.
    Abstract: A Fast Factorized Backprojection scheme modified to X-band frequencies and applicable to small aperture beamwidths is presented to compute SAR images from real and synthetic airborne data sets. The numerical complexity and memory consumption of the algorithm is verified and compared to ordinary Backprojection. The modified Fast Factorized Backprojection scheme is investigated for exceedingly curved flight paths and compared to an \u03c9-k algorithm in combination with a motion error correction. Excellent SAR image focusing results were found for the modified Fast Factorized Backprojection approach while keeping the numerical complexity to O(N2log(N)).

    @InProceedings{brandfassLobiancoEUSAR2008:FFBPforXBand,
    Title = {Modified Fast Factorized Backprojection as Applied to X-Band Data for Curved Flight Paths},
    Author = {Brandfass, Michael and Lobianco, Luis Fernando},
    Booktitle = {European Conference on Synthetic Aperture Radar (EUSAR)},
    ISBN = {978-3-8007-3084-1},
    Location = {Friedrichshafen, Germany},
    Month = {jun},
    Pages = {4},
    Publisher = {VDE Verlag GmbH},
    Url = {http://www.vde-verlag.de/data/prcd.php?docid=453084017&loc=de},
    Year = {2008},
    Abstract = {A Fast Factorized Backprojection scheme modified to X-band frequencies and applicable to small aperture beamwidths is presented to compute SAR images from real and synthetic airborne data sets. The numerical complexity and memory consumption of the algorithm is verified and compared to ordinary Backprojection. The modified Fast Factorized Backprojection scheme is investigated for exceedingly curved flight paths and compared to an \u03c9-k algorithm in combination with a motion error correction. Excellent SAR image focusing results were found for the modified Fast Factorized Backprojection approach while keeping the numerical complexity to O(N2log(N)).},
    Keywords = {SAR Processsing, Time-Domain Back-Projection, TDBP, Back-Projection, Fast Factorized Back-Projection, FFBP, Fast Back-Projection, Synthetic Aperture Radar (SAR), motion compensation, tomography, Airborne SAR,X-Band, Motion Compensation, MoComp, Non-Linear SAR, Non-Linear Flight Tracks},
    Owner = {ofrey},
    Pdf = {../../../docs/brandfassLobiancoEUSAR2008.pdf} 
    }
    


  3. Honglei Chen and D. Kasilingam. Performance Analysis of Multivariate Super-resolution Processing of Polarimetric Synthetic Aperture Radar Tomography. In Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International, volume 4, pages 169-172, July 2008.
    @InProceedings{Chen2008,
    Title = {Performance Analysis of Multivariate Super-resolution Processing of Polarimetric Synthetic Aperture Radar Tomography},
    Author = {Honglei Chen and Kasilingam, D.},
    Booktitle = {Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International},
    Doi = {10.1109/IGARSS.2008.4779684},
    Month = jul,
    Pages = {169--172},
    Volume = {4},
    Year = {2008},
    Owner = {ofrey},
    Timestamp = {2009.07.01} 
    }
    


  4. A. Donnellan, P. Rosen, J. Graf, A. Loverro, A. Freeman, R. Treuhaft, R. Oberto, Marc Simard, Eric J. Rignot, R. Kwok, Xiaoqing Pi, J.B. Blair, W. Abdalati, J. Ranson, H. Zebker, B. Hager, H. Shugart, M. Fahnestock, and R. Dubayah. Deformation, Ecosystem Structure, and Dynamics of Ice (DESDynI). In Proc. IEEE Aerospace Conf., pages 1-13, March 2008. Keyword(s): DESDynl mission, National Research Council Earth Science Decadal Survey, Earth Science Applications from Space, biomass, cryosphere objectives, ecosystem function, ecosystem structure, ice dynamics, integrated L-band InSAR, multibeam Lidar mission, solid Earth, surface deformation, topography, vegetation structure, deformation, optical radar, synthetic aperture radar, topography (Earth), vegetation mapping.
    Abstract: The National Research Council Earth Science Decadal Survey, Earth Science Applications from Space, recommends that DESDynl (Deformation, Ecosystem Structure, and Dynamics of Ice), an integrated L-band InSAR and multibeam Lidar mission, launch in the 2010- 2013 timeframe. The mission will measure surface deformation for solid Earth and cryosphere objectives and vegetation structure for understanding the carbon cycle. InSAR has been used to study surface deformation of the solid Earth and cryosphere and more recently vegetation structure for estimates of biomass and ecosystem function. Lidar directly measures topography and vegetation structure and is used to estimate biomass and detect changes in surface elevation. The goal of DESDynl is to take advantage of the spatial continuity of InSAR and precision and directness of Lidar. There are several issues related to the design of the DESDynl mission, including combining the two instruments into a single platform, optimizing the coverage and orbit for the two techniques, and carrying out the science modeling to define and maximize the scientific output of the mission.

    @InProceedings{DonnellanEtAl2008:DESDynI,
    Title = {Deformation, Ecosystem Structure, and Dynamics of Ice ({DESDynI})},
    Author = {Donnellan, A. and Rosen, P. and Graf, J. and Loverro, A. and Freeman, A. and Treuhaft, R. and Oberto, R. and Simard, Marc and Rignot, Eric J. and Kwok, R. and Xiaoqing Pi and Blair, J.B. and Abdalati, W. and Ranson, J. and Zebker, H. and Hager, B. and Shugart, H. and Fahnestock, M. and Dubayah, R.},
    Booktitle = {Proc. IEEE Aerospace Conf.},
    Doi = {10.1109/AERO.2008.4526249},
    Month = mar,
    Pages = {1-13},
    Year = {2008},
    Abstract = {The National Research Council Earth Science Decadal Survey, Earth Science Applications from Space, recommends that DESDynl (Deformation, Ecosystem Structure, and Dynamics of Ice), an integrated L-band InSAR and multibeam Lidar mission, launch in the 2010- 2013 timeframe. The mission will measure surface deformation for solid Earth and cryosphere objectives and vegetation structure for understanding the carbon cycle. InSAR has been used to study surface deformation of the solid Earth and cryosphere and more recently vegetation structure for estimates of biomass and ecosystem function. Lidar directly measures topography and vegetation structure and is used to estimate biomass and detect changes in surface elevation. The goal of DESDynl is to take advantage of the spatial continuity of InSAR and precision and directness of Lidar. There are several issues related to the design of the DESDynl mission, including combining the two instruments into a single platform, optimizing the coverage and orbit for the two techniques, and carrying out the science modeling to define and maximize the scientific output of the mission.},
    ISSN = {1095-323X},
    Keywords = {DESDynl mission;National Research Council Earth Science Decadal Survey, Earth Science Applications from Space;biomass;cryosphere objectives;ecosystem function;ecosystem structure;ice dynamics;integrated L-band InSAR;multibeam Lidar mission;solid Earth;surface deformation;topography;vegetation structure;deformation;optical radar;synthetic aperture radar;topography (Earth);vegetation mapping} 
    }
    


  5. A. Donnellan, P. Rosen, J. Ranson, and H. Zebker. Deformation, Ecosystem Structure, and Dynamics of Ice (DESDynI). In IEEE Int. Geoscience and Remote Sensing Symposium, IGARSS 2008, volume 3, pages 5-8, July 2008. Keyword(s): DESDynl mission, Deformation, Ecosystem Structure, and Dynamics of Ice, Earth Science Decadal Survey, National Research Council, biomass estimation, carbon cycle, cryosphere objectives, ecosystem function, integrated L-band InSAR, multibeam Lidar mission, solid Earth surface deformation, surface elevation changes, topography measure, vegetation structure, deformation, optical radar, radar interferometry, remote sensing by radar, topography (Earth), vegetation.
    Abstract: The National Research Council Earth Science Decadal Survey, Earth Science Applications from Space, recommends that DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice), an integrated L-band InSAR and multibeam Lidar mission, launch in the 2010-2013 timeframe. The mission will measure surface deformation for solid Earth and cryosphere objectives and vegetation structure for understanding the carbon cycle. InSAR has been used to study surface deformation of the solid Earth and cryosphere and more recently vegetation structure for estimates of biomass and ecosystem function. Lidar directly measures topography and vegetation structure and is used to estimate biomass and detect changes in surface elevation. The goal of DESDynI is to take advantage of the spatial continuity of InSAR and the precision and directness of Lidar. There are several issues related to the design of the DESDynI mission, including combining the two instruments into a single platform, optimizing the coverage and orbit for the two techniques, and carrying out the science modeling to define and maximize the scientific output of the mission.

    @InProceedings{DonnellanRosenRansonZebker2008:DESDynI,
    Title = {Deformation, Ecosystem Structure, and Dynamics of Ice ({DESDynI})},
    Author = {Donnellan, A. and Rosen, P. and Ranson, J. and Zebker, H.},
    Booktitle = {IEEE Int. Geoscience and Remote Sensing Symposium, IGARSS 2008},
    Doi = {10.1109/IGARSS.2008.4779268},
    Month = jul,
    Pages = {5-8},
    Volume = {3},
    Year = {2008},
    Abstract = {The National Research Council Earth Science Decadal Survey, Earth Science Applications from Space, recommends that DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice), an integrated L-band InSAR and multibeam Lidar mission, launch in the 2010-2013 timeframe. The mission will measure surface deformation for solid Earth and cryosphere objectives and vegetation structure for understanding the carbon cycle. InSAR has been used to study surface deformation of the solid Earth and cryosphere and more recently vegetation structure for estimates of biomass and ecosystem function. Lidar directly measures topography and vegetation structure and is used to estimate biomass and detect changes in surface elevation. The goal of DESDynI is to take advantage of the spatial continuity of InSAR and the precision and directness of Lidar. There are several issues related to the design of the DESDynI mission, including combining the two instruments into a single platform, optimizing the coverage and orbit for the two techniques, and carrying out the science modeling to define and maximize the scientific output of the mission.},
    Keywords = {DESDynl mission;Deformation, Ecosystem Structure, and Dynamics of Ice;Earth Science Decadal Survey;National Research Council;biomass estimation;carbon cycle;cryosphere objectives;ecosystem function;integrated L-band InSAR;multibeam Lidar mission;solid Earth surface deformation;surface elevation changes;topography measure;vegetation structure;deformation;optical radar;radar interferometry;remote sensing by radar;topography (Earth);vegetation} 
    }
    


  6. H. Essen, T. Brehm, M. Haegelen, and H. Schimpf. Remote Sensing at Millimetre Waves with the MEMPHIS Synthetic Aperture Radar. In Proc. European Conf. Synthetic Aperture Radar, pages 1-4, June 2008. Keyword(s): SAR Processing, W-Band, SUMATRA, Airborne SAR, UAV, Fraunhofer, Acceleration, Image resolution, Radar imaging, Remote sensing, Synthetic aperture radar.
    Abstract: Synthetic Aperture Radar (SAR) is a tool for a broad community and a range of different applications. Especially for remote sensing applications data with high resolution preferably in all three dimensions are requested to provide the users with images of the earth's surface in high quality at any time regardless of cloud cover or time of the day. This is possible within quick reaction times, if an aircraft is taken as sensor platform. For the mapping of smaller areas with high precision, millimetre wave SAR offers best opportunities, combining all advantages of SAR imaging with ease of processing and the capability to be operated from small and light aircrafts, even remotely piloted. To show the advantages of these radar bands for remote sensing applications and especially to allow simultaneous comparative measurements at both relevant millimetre wave atmospheric windows, Ka- and W-band, the experimental SAR sensor MEMPHIS (Millimeterwave experimental multifrequency polarimetric high resolution imaging sensor) was developed and has been improved and extended in its capability over recent years. The paper gives a description of the present state of the system and presents representative examples for remote sensing applications.

    @InProceedings{EssenEtAlEUSAR2008MEMPHISWBandKaBand,
    author = {H. Essen and T. Brehm and M. Haegelen and H. Schimpf},
    booktitle = {Proc. European Conf. Synthetic Aperture Radar},
    title = {Remote Sensing at Millimetre Waves with the {MEMPHIS} Synthetic Aperture Radar},
    year = {2008},
    month = jun,
    pages = {1-4},
    abstract = {Synthetic Aperture Radar (SAR) is a tool for a broad community and a range of different applications. Especially for remote sensing applications data with high resolution preferably in all three dimensions are requested to provide the users with images of the earth's surface in high quality at any time regardless of cloud cover or time of the day. This is possible within quick reaction times, if an aircraft is taken as sensor platform. For the mapping of smaller areas with high precision, millimetre wave SAR offers best opportunities, combining all advantages of SAR imaging with ease of processing and the capability to be operated from small and light aircrafts, even remotely piloted. To show the advantages of these radar bands for remote sensing applications and especially to allow simultaneous comparative measurements at both relevant millimetre wave atmospheric windows, Ka- and W-band, the experimental SAR sensor MEMPHIS (Millimeterwave experimental multifrequency polarimetric high resolution imaging sensor) was developed and has been improved and extended in its capability over recent years. The paper gives a description of the present state of the system and presents representative examples for remote sensing applications.},
    keywords = {SAR Processing, W-Band,SUMATRA, Airborne SAR, UAV, Fraunhofer,Acceleration;Image resolution;Radar imaging;Remote sensing;Synthetic aperture radar},
    owner = {ofrey},
    
    }
    


  7. G. Fornaro, A. Pauciullo, F. Lombardini, and M. Pardini. Detection of Single and Multiple Scatterers in Multibaseline Multitemporal SAR Data. In Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International, volume 2, pages 453-456, July 2008.
    @InProceedings{Fornaro2008,
    Title = {Detection of Single and Multiple Scatterers in Multibaseline Multitemporal SAR Data},
    Author = {Fornaro, G. and Pauciullo, A. and Lombardini, F. and Pardini, M.},
    Booktitle = {Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International},
    Doi = {10.1109/IGARSS.2008.4779026},
    Month = jul,
    Pages = {453--456},
    Volume = {2},
    Year = {2008},
    Owner = {ofrey},
    Timestamp = {2009.07.01} 
    }
    


  8. Othmar Frey, Christophe Magnard, Maurice Rüegg, and Erich Meier. Focusing SAR Data Acquired From Non-Linear Sensor Trajectories. In Proc. IEEE Int. Geosci. Remote Sens. Symp., pages 415-418, 2008. Keyword(s): SAR Processing, Time-Domain Back-Projection, Back-Projection, Nonlinear Flight Tracks, Curvilinear SAR, Extended Chirp Scaling, ECS, Mosaicking, Geocoding, Integrated Focusing and Geocoding, Georeferencing, mapping, corridor mapping, E-SAR, L-Band, digital elevation model, Airborne SAR.
    Abstract: Standard focusing of SAR data assumes a straight recording track of the sensor platform. Small non-linearities of airborne platform tracks are corrected for during a motion compensation step while keeping the assumption of a linear flight path. In the following, the processing of SAR data from nonlinear tracks is discussed as may originate from small aircraft or drones flying at low altitude. They fly not a straight track but one dependent on topography, influences of weather and wind, or dependent on the shape of dedicated areas of interest such as rivers or traffic routes. A time-domain backprojection based technique, is proposed and evaluated with the help of experimental data featuring a drop in height, a double bend, a 90-degree curve and a linear flight track. In order to assess the quality of the focused data, close-ups of amplitude images are compared and the coherence is evaluated. The experimental data was acquired by the German Aerospace Center's E-SAR L-band system.

    @InProceedings{freyMagnardRueeggMeier08Igarss:Tracks,
    author = {Othmar Frey and Christophe Magnard and Maurice R{\"u}egg and Erich Meier},
    title = {{Focusing SAR Data Acquired From Non-Linear Sensor Trajectories}},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2008},
    pages = {415-418},
    abstract = {Standard focusing of SAR data assumes a straight recording track of the sensor platform. Small non-linearities of airborne platform tracks are corrected for during a motion compensation step while keeping the assumption of a linear flight path. In the following, the processing of SAR data from nonlinear tracks is discussed as may originate from small aircraft or drones flying at low altitude. They fly not a straight track but one dependent on topography, influences of weather and wind, or dependent on the shape of dedicated areas of interest such as rivers or traffic routes. A time-domain backprojection based technique, is proposed and evaluated with the help of experimental data featuring a drop in height, a double bend, a 90-degree curve and a linear flight track. In order to assess the quality of the focused data, close-ups of amplitude images are compared and the coherence is evaluated. The experimental data was acquired by the German Aerospace Center's E-SAR L-band system.},
    file = {:freyMagnardRueeggMeier08IgarssTracks.pdf:PDF},
    keywords = {SAR Processing, Time-Domain Back-Projection, Back-Projection, Nonlinear Flight Tracks, Curvilinear SAR, Extended Chirp Scaling, ECS, Mosaicking, Geocoding, Integrated Focusing and Geocoding, Georeferencing, mapping, corridor mapping, E-SAR, L-Band, digital elevation model, Airborne SAR},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMagnardRueeggMeier08IgarssTracks.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4779746&isnumber=4779630},
    
    }
    


  9. Othmar Frey, Christophe Magnard, Maurice Rüegg, and Erich Meier. Non-Linear SAR Data Processing By Time-Domain Back-Projection. In Proc. EUSAR 2008 - 7th European Conference on Synthetic Aperture Radar, pages 165-168, 2008. Keyword(s): SAR Processing, Time-Domain Back-Projection, Back-Projection, Non-Linear Flight Tracks, Curvilinear SAR, Extended Chirp Scaling, ECS, Mosaicking, Geocoding, Integrated Focusing and Geocoding, Georeferencing, mapping, corridor mapping.E-SAR, L-Band, digital elevation model, Airborne SAR.
    Abstract: Focusing of conventional stripmap SAR data assumes a straight recording track of the sensor platform. Small deviations from that linear trajectory are corrected by motion compensation steps while keeping the assumption of a linear acquisition path. In the following, the processing of SAR data from non-linear tracks is discussed as may originate from small aircraft or drones flying at low altitude. They fly not a straight track but one dependent on topography, influences of weather and wind, or dependent on the shape of dedicated areas of interest such as rivers or traffic routes. Experimental data featuring a drop in height, a double bend and a 90-degree curve have been processed using a time-domain back-projection approach. The data was acquired by the German Aerospace Center's E-SAR L-band system.

    @InProceedings{freyMagnardRueeggMeier08Eusar:Tracks,
    author = {Othmar Frey and Christophe Magnard and Maurice R{\"u}egg and Erich Meier},
    title = {{Non-Linear SAR Data Processing By Time-Domain Back-Projection}},
    booktitle = {Proc. EUSAR 2008 - 7th European Conference on Synthetic Aperture Radar},
    year = {2008},
    pages = {165-168},
    abstract = {Focusing of conventional stripmap SAR data assumes a straight recording track of the sensor platform. Small deviations from that linear trajectory are corrected by motion compensation steps while keeping the assumption of a linear acquisition path. In the following, the processing of SAR data from non-linear tracks is discussed as may originate from small aircraft or drones flying at low altitude. They fly not a straight track but one dependent on topography, influences of weather and wind, or dependent on the shape of dedicated areas of interest such as rivers or traffic routes. Experimental data featuring a drop in height, a double bend and a 90-degree curve have been processed using a time-domain back-projection approach. The data was acquired by the German Aerospace Center's E-SAR L-band system.},
    file = {:freyMagnardRueeggMeier08EusarTracks.pdf:PDF},
    keywords = {SAR Processing, Time-Domain Back-Projection, Back-Projection, Non-Linear Flight Tracks, Curvilinear SAR, Extended Chirp Scaling, ECS, Mosaicking, Geocoding, Integrated Focusing and Geocoding, Georeferencing, mapping, corridor mapping.E-SAR, L-Band, digital elevation model, Airborne SAR},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMagnardRueeggMeier08EusarTracks.pdf},
    
    }
    


  10. Othmar Frey and Erich Meier. Combining Time-Domain Back-Projection and Capon Beamforming for Tomographic SAR Processing. In Proc. IEEE Int. Geosci. Remote Sens. Symp., pages 445-448, 2008. Keyword(s): SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry, Capon, Capon Beamforming, Superresolution.
    Abstract: Various tomographic processing methods have been investigated in recent years. The quality of the focused tomographic image is usually limited by several factors. In particular, Fourier-based focusing methods are susceptible to irregular and sparse sampling, two problems that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. Neither time-domain back-projection (TDBP) processing, although providing a very accurate processing framework, is able to overcome the problem of ambiguous target detection in the tomographic image. In this paper, a possible extension of the TDBP approach to multilooking based tomographic focusing methods like standard beamforming and Capon beamforming is discussed. Preliminary results obtained with a simulated and a real airborne tomographic P-band data set are shown.

    @InProceedings{freyMeier08Igarss:Tomo,
    author = {Othmar Frey and Erich Meier},
    title = {{Combining Time-Domain Back-Projection and Capon Beamforming for Tomographic SAR Processing}},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2008},
    pages = {445-448},
    abstract = {Various tomographic processing methods have been investigated in recent years. The quality of the focused tomographic image is usually limited by several factors. In particular, Fourier-based focusing methods are susceptible to irregular and sparse sampling, two problems that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. Neither time-domain back-projection (TDBP) processing, although providing a very accurate processing framework, is able to overcome the problem of ambiguous target detection in the tomographic image. In this paper, a possible extension of the TDBP approach to multilooking based tomographic focusing methods like standard beamforming and Capon beamforming is discussed. Preliminary results obtained with a simulated and a real airborne tomographic P-band data set are shown.},
    file = {:freyMeier08IgarssTomo.pdf:PDF},
    keywords = {SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry,Capon, Capon Beamforming, Superresolution},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMeier08IgarssTomo.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4779024&isnumber=4778902},
    
    }
    


  11. Othmar Frey and Erich Meier. Tomographic Focusing by Combining Time-Domain Back-Projection and Multi-Looking Based Focusing Techniques. In Proc. EUSAR 2008 - 7th European Conference on Synthetic Aperture Radar, pages 73-76, 2008. Keyword(s): SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry, Capon, Capon Beamforming, Superresolution.
    Abstract: Various tomographic processing methods have been investigated in recent years. The quality of the focused tomographic image is usually limited by several factors. In particular, Fourier-based focusing methods are susceptible to irregular and sparse sampling, two problems that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. Neither time-domain back-projection (TDBP) processing, although providing a very accurate processing framework, is able to overcome the problem of ambiguous target detection in the tomographic image. In this paper, a possible extension of the TDBP approach to multi-looking based tomographic focusing methods like standard beamforming and Capon beamforming is discussed.

    @InProceedings{freyMeier08Eusar:Tomo,
    author = {Othmar Frey and Erich Meier},
    title = {{Tomographic Focusing by Combining Time-Domain Back-Projection and Multi-Looking Based Focusing Techniques}},
    booktitle = {Proc. EUSAR 2008 - 7th European Conference on Synthetic Aperture Radar},
    year = {2008},
    pages = {73-76},
    abstract = {Various tomographic processing methods have been investigated in recent years. The quality of the focused tomographic image is usually limited by several factors. In particular, Fourier-based focusing methods are susceptible to irregular and sparse sampling, two problems that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. Neither time-domain back-projection (TDBP) processing, although providing a very accurate processing framework, is able to overcome the problem of ambiguous target detection in the tomographic image. In this paper, a possible extension of the TDBP approach to multi-looking based tomographic focusing methods like standard beamforming and Capon beamforming is discussed.},
    file = {:freyMeier08EusarTomo.pdf:PDF},
    keywords = {SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry, Capon, Capon Beamforming, Superresolution},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMeier08EusarTomo.pdf},
    
    }
    


  12. M. Haegelen, G. Briese, H. Essen, and A. Tessmann. Millimetre Wave Near Field SAR Scanner for Concealed Weapon Detection. In 7th European Conference on Synthetic Aperture Radar, pages 1-4, June 2008. Keyword(s): SAR Processing, W-Band, Apertures, Geometry, Radar imaging, Security, Sensors, Weapons.
    Abstract: A light weight, transportable measurement system for the inspection of suspicious humans and of luggage in a threat situation has been developed, based upon miniaturized millimetre wave radar modules operating at W-band. To allow a sufficient detection capability of objects hidden under the clothing or within a piece of luggage within buildings at a sufficiently short scanning time, a radar approach rather than a passive radiometer technique was chosen. It is generally recognized, that only synthetic aperture is able to supply a sufficient geometrical resolution at high imaging speed. Moreover a radar can also deliver a three dimensional description for the position and the shape of a concealed object using high range resolution techniques. The paper describes the measurement set-up and the evaluation algorithm. Typical examples for different set-ups are presented.

    @INPROCEEDINGS{haegelenBrieseEssenTessmannEUSAR2008wbandCloseRangeSAR,
    author={M. Haegelen and G. Briese and H. Essen and A. Tessmann},
    booktitle={7th European Conference on Synthetic Aperture Radar},
    title={Millimetre Wave Near Field SAR Scanner for Concealed Weapon Detection},
    year={2008},
    volume={},
    number={},
    pages={1-4},
    abstract={A light weight, transportable measurement system for the inspection of suspicious humans and of luggage in a threat situation has been developed, based upon miniaturized millimetre wave radar modules operating at W-band. To allow a sufficient detection capability of objects hidden under the clothing or within a piece of luggage within buildings at a sufficiently short scanning time, a radar approach rather than a passive radiometer technique was chosen. It is generally recognized, that only synthetic aperture is able to supply a sufficient geometrical resolution at high imaging speed. Moreover a radar can also deliver a three dimensional description for the position and the shape of a concealed object using high range resolution techniques. The paper describes the measurement set-up and the evaluation algorithm. Typical examples for different set-ups are presented.},
    keywords={SAR Processing, W-Band,Apertures;Geometry;Radar imaging;Security;Sensors;Weapons},
    doi={},
    ISSN={},
    month=jun,
    owner = {ofrey},
    
    }
    


  13. Charles V. Jakowatz, Daniel E. Wahl, and David A. Yocky. Beamforming as a foundation for spotlight-mode SAR image formation by backprojection. In Edmund G. Zelnio and Frederick D. Garber, editors, , volume 6970, pages 69700Q, 2008. SPIE. Keyword(s): SAR Processing, Back-projection, Time-Domain Back-Projection, TDBP, Fast Back-projection, Fast Factorized Back-Projection, FFBP, Spotlight SAR, Spotlight-mode data, Beamforming.
    @Conference{jakowatzWahlYockyBeamformingTDBPSpotlightMode2008,
    author = {Charles V. Jakowatz and Daniel E. Wahl and David A. Yocky},
    title = {Beamforming as a foundation for spotlight-mode {SAR} image formation by backprojection},
    year = {2008},
    editor = {Edmund G. Zelnio and Frederick D. Garber},
    volume = {6970},
    number = {1},
    pages = {69700Q},
    publisher = {SPIE},
    doi = {10.1117/12.779305},
    eid = {69700Q},
    file = {:jakowatzWahlYockyBeamformingTDBPSpotlightMode2008.pdf:PDF},
    journal = {Algorithms for Synthetic Aperture Radar Imagery XV},
    keywords = {SAR Processing, Back-projection, Time-Domain Back-Projection, TDBP, Fast Back-projection, Fast Factorized Back-Projection, FFBP, Spotlight SAR, Spotlight-mode data, Beamforming},
    location = {Orlando, FL, USA},
    numpages = {15},
    owner = {ofrey},
    pdf = {../../../docs/jakowatzWahlYockyBeamformingTDBPSpotlightMode2008.pdf},
    url = {http://link.aip.org/link/?PSI/6970/69700Q/1},
    
    }
    


  14. F. Lombardini, G. Fornaro, M. Pardini, D. Reale, F. Serafino, F. Soldovieri, and M. Costantini. SAR tomography for scene elevation and deformation reconstruction: Algorithms and potentialities. In Radar Conference, 2008. RADAR '08. IEEE, pages 1-7, May 2008.
    @InProceedings{Lombardini2008,
    Title = {SAR tomography for scene elevation and deformation reconstruction: Algorithms and potentialities},
    Author = {Lombardini, F. and Fornaro, G. and Pardini, M. and Reale, D. and Serafino, F. and Soldovieri, F. and Costantini, M.},
    Booktitle = {Radar Conference, 2008. RADAR '08. IEEE},
    Doi = {10.1109/RADAR.2008.4720739},
    Month = may,
    Pages = {1--7},
    Year = {2008},
    Owner = {ofrey},
    Timestamp = {2009.07.01} 
    }
    


  15. Christophe Magnard, Othmar Frey, Maurice Rüegg, and Erich Meier. Improved Airborne SAR Data Processing by Blockwise Focusing, Mosaicking and Geocoding. In Proc. EUSAR 2008 - 7th European Conference on Synthetic Aperture Radar, pages 375-378, 2008. Keyword(s): SAR Processing, Time-Domain Back-Projection, Back-Projection, Non-Linear Flight Tracks, Curvilinear SAR, Extended Chirp Scaling, ECS, Mosaicking, Geocoding, Integrated Focusing and Geocoding, Georeferencing, mapping, corridor mapping.E-SAR, L-Band, digital elevation model, Airborne SAR.
    Abstract: Standard focusing of SAR data assumes a straight recording track of the sensor platform. Small non-linearities of airborne platform are corrected for during a motion compensation step while keeping the assumption of a stripmap geometry. In the case of high resolution and high frequency SAR systems, the navigation data may not be accurate enough to perform such a motion compensation; SAR systems mounted on small aircrafts or drones flying at low altitude do not follow a straight track but one dependent on topography and atmospheric conditions. We present a blockwise focusing, mosaicking and geocoding method which allows processing such data. For the experiments, MEMPHIS and E-SAR data were used.

    @InProceedings{magnardFreyRueeggMeier08Eusar:Tracks,
    author = {Christophe Magnard and Othmar Frey and Maurice R{\"u}egg and Erich Meier},
    title = {{Improved Airborne SAR Data Processing by Blockwise Focusing, Mosaicking and Geocoding}},
    booktitle = {Proc. EUSAR 2008 - 7th European Conference on Synthetic Aperture Radar},
    year = {2008},
    pages = {375-378},
    abstract = {Standard focusing of SAR data assumes a straight recording track of the sensor platform. Small non-linearities of airborne platform are corrected for during a motion compensation step while keeping the assumption of a stripmap geometry. In the case of high resolution and high frequency SAR systems, the navigation data may not be accurate enough to perform such a motion compensation; SAR systems mounted on small aircrafts or drones flying at low altitude do not follow a straight track but one dependent on topography and atmospheric conditions. We present a blockwise focusing, mosaicking and geocoding method which allows processing such data. For the experiments, MEMPHIS and E-SAR data were used.},
    file = {:magnardFreyRueeggMeier08EusarTracks.pdf:PDF},
    keywords = {SAR Processing, Time-Domain Back-Projection, Back-Projection, Non-Linear Flight Tracks, Curvilinear SAR, Extended Chirp Scaling, ECS, Mosaicking, Geocoding, Integrated Focusing and Geocoding, Georeferencing, mapping, corridor mapping.E-SAR, L-Band, digital elevation model, Airborne SAR},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/magnardFreyRueeggMeier08EusarTracks.pdf},
    
    }
    


  16. G. Margarit, Jordi J. Mallorqui, I. Corney, and C. Lopez-Martinez. A Public Database of Simulated Multidimensional SAR Data for Techniques Validation. In Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International, volume 2, pages 601-604, July 2008.
    @InProceedings{Margarit2008,
    Title = {A Public Database of Simulated Multidimensional SAR Data for Techniques Validation},
    Author = {Margarit, G. and Mallorqui, Jordi J. and Corney, I. and Lopez-Martinez, C.},
    Booktitle = {Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International},
    Doi = {10.1109/IGARSS.2008.4779064},
    Month = jul,
    Pages = {601--604},
    Volume = {2},
    Year = {2008},
    Owner = {ofrey} 
    }
    


  17. Thierry Michel and Scott Hensley. Wavenumber domain focusing of squinted SAR data with a curved orbit geometry. In Proc. 42nd Asilomar Conf. on Signals, Systems and Computers, pages 492-496, October 2008. Keyword(s): SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Curvilinear SAR, airborne SAR, SAR data, curved orbit geometry, squinted geometry, synthetic aperture radar, wavenumber domain focusing, synthetic aperture radar.
    Abstract: Synthetic Aperture Radar systems provide raw data that need focusing to achieve full-resolution imaging. Current SAR applications, including interferometry, require accurate, phase-preserving, and precisely co-registered coherent images over large ground swaths with the highest achievable resolution. In addition to these challenges, stripmap SAR data may be acquired with an off-broadside (squinted) geometry, either by design or through platform motion. The precise batch focusing of these large aperture and wide bandwidth data sets is known to require a 2D frequency processing approach. The standard wave domain focusing algorithm, however, is only exact for data acquired on a rectilinear trajectory. We investigate a generalization of the standard omega-k focusing formulation that allows curved data acquisition tracks. The new formulation can be used in conjunction with a known extension for conical, squinted imaging grids. The approximations necessary to allow the generalized geometry are analysed to determines the range of applicability of the proposed algorithm. The theory is validated using data simulated with parameters similar to the UAVSAR L-band SAR system.

    @InProceedings{michelHensley2008,
    author = {Michel, Thierry and Hensley, Scott},
    title = {Wavenumber domain focusing of squinted {SAR} data with a curved orbit geometry},
    booktitle = {Proc. 42nd Asilomar Conf. on Signals, Systems and Computers},
    year = {2008},
    pages = {492-496},
    month = oct,
    abstract = {Synthetic Aperture Radar systems provide raw data that need focusing to achieve full-resolution imaging. Current SAR applications, including interferometry, require accurate, phase-preserving, and precisely co-registered coherent images over large ground swaths with the highest achievable resolution. In addition to these challenges, stripmap SAR data may be acquired with an off-broadside (squinted) geometry, either by design or through platform motion. The precise batch focusing of these large aperture and wide bandwidth data sets is known to require a 2D frequency processing approach. The standard wave domain focusing algorithm, however, is only exact for data acquired on a rectilinear trajectory. We investigate a generalization of the standard omega-k focusing formulation that allows curved data acquisition tracks. The new formulation can be used in conjunction with a known extension for conical, squinted imaging grids. The approximations necessary to allow the generalized geometry are analysed to determines the range of applicability of the proposed algorithm. The theory is validated using data simulated with parameters similar to the UAVSAR L-band SAR system.},
    doi = {10.1109/ACSSC.2008.5074454},
    file = {:michelHensley2008.pdf:PDF},
    issn = {1058-6393},
    keywords = {SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Curvilinear SAR, airborne SAR, SAR data;curved orbit geometry;squinted geometry;synthetic aperture radar;wavenumber domain focusing;synthetic aperture radar},
    owner = {ofrey},
    pdf = {../../../docs/michelHensley2008.pdf},
    
    }
    


  18. Matteo Nannini, Rolf Scheiber, and Alberto Moreira. On the Minimum Number of Tracks for SAR Tomography. In Proc. IEEE Int. Geosci. Remote Sens. Symp., volume 2, pages 441-444, July 2008. Keyword(s): SAR Processing, SAR Tomography, Capon, MUSIC, image reconstruction, airboren SAR, image representation, radar interferometry, synthetic aperture radar3D representation, German Aerospace Center, DLR, L-band, SAR interferometry, SARTom, data acquisition, equivalent targets, experimental SAR system, minimum tomographic aperture, spheroidal wave functions, subspace superresolution methods, synthetic aperture radar tomography, tracks minimum number determination, volumetric source, ESAR.
    Abstract: The main drawback of SAR Tomography (SARTom) is the considerable number of tracks required to achieve the 3-dimensional (3D) representation of a viewed scene. The key point concerns the trade-off between the vertical resolution and the control on ambiguities phenomena. This paper deals with the problem of the determination of the minimum number of required tracks when super-resolution subspace methods are applied. The results are validated on real data acquired in L-band by the E-SAR system of the German Aerospace Centre.

    @InProceedings{nanniniScheiberMoreira2008:SARTom,
    Title = {{On the Minimum Number of Tracks for SAR Tomography}},
    Author = {Nannini, Matteo and Scheiber, Rolf and Moreira, Alberto},
    Booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    Doi = {10.1109/IGARSS.2008.4779023},
    Month = jul,
    Pages = {441-444},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4779023&isnumber=4778902},
    Volume = {2},
    Year = {2008},
    Abstract = {The main drawback of SAR Tomography (SARTom) is the considerable number of tracks required to achieve the 3-dimensional (3D) representation of a viewed scene. The key point concerns the trade-off between the vertical resolution and the control on ambiguities phenomena. This paper deals with the problem of the determination of the minimum number of required tracks when super-resolution subspace methods are applied. The results are validated on real data acquired in L-band by the E-SAR system of the German Aerospace Centre.},
    Keywords = {SAR Processing, SAR Tomography, Capon, MUSIC, image reconstruction, airboren SAR, image representation, radar interferometry, synthetic aperture radar3D representation, German Aerospace Center, DLR, L-band, SAR interferometry, SARTom, data acquisition, equivalent targets, experimental SAR system, minimum tomographic aperture, spheroidal wave functions, subspace superresolution methods, synthetic aperture radar tomography, tracks minimum number determination, volumetric source, ESAR},
    Owner = {ofrey},
    Pdf = {../../../docs/nanniniScheiberMoreira2008.pdf} 
    }
    


  19. P.A. Rosen, S. Hensley, and C. Le. Observations and mitigation of RFI in ALOS PALSAR SAR data: Implications for the DESDynI mission. In IEEE Radar Conference, pages 1-6, May 2008. Keyword(s): DESDynI mission, L-band polarimetric radar, RFI, SAR data, radio frequency interference, synthetic aperture radar, radiofrequency interference, synthetic aperture radar.
    Abstract: Initial examination of ALOS PALSAR synthetic aperture radar (SAR) data has indicated significant radio frequency interference (RFI) in several geographic locations around the world. RFI causes significant reduction in image contrast, introduces periodic and quasi-periodic image artifacts, and introduces significant phase noise in repeat-pass interferometric data reduction. The US National Research Council Decadal Survey of Earth Science has recommended DESDynI, a Deformation, Ecosystem Structure, and Dynamics of Ice satellite mission comprising an L-band polarimetric radar configured for repeat-pass interferometry. There is considerable interest internationally in other future L-band and lower frequency systems, as well. Therefore, the issues of prevalence and possibilities of mitigation of RFI in these crowded frequency bands are of considerable interest. RFI is observed in ALOS PALSAR in California and Hawaii, USA, and in southern Egypt in data examined to date. Application of several techniques for removing it from the data prior to SAR image formation, ranging from straight-forward spectral normalization to time-domain, multi-phase filtering techniques, are considered. Considerable experience has been gained from the removal of RFI from P-band acquired by the GeoSAR system. These techniques applied to the PALSAR data are most successful when the bandwidth of any particular spectral component of the RFI is narrow. Performance impacts for SAR imagery and interferograms are considered in the context of DESDynI measurement requirements.

    @InProceedings{RosenHensleyLe2008:DESDynIandRFI,
    Title = {Observations and mitigation of RFI in ALOS PALSAR SAR data: Implications for the DESDynI mission},
    Author = {Rosen, P.A. and Hensley, S. and Le, C.},
    Booktitle = {IEEE Radar Conference},
    Doi = {10.1109/RADAR.2008.4720738},
    Month = {may},
    Pages = {1-6},
    Year = {2008},
    Abstract = {Initial examination of ALOS PALSAR synthetic aperture radar (SAR) data has indicated significant radio frequency interference (RFI) in several geographic locations around the world. RFI causes significant reduction in image contrast, introduces periodic and quasi-periodic image artifacts, and introduces significant phase noise in repeat-pass interferometric data reduction. The US National Research Council Decadal Survey of Earth Science has recommended DESDynI, a Deformation, Ecosystem Structure, and Dynamics of Ice satellite mission comprising an L-band polarimetric radar configured for repeat-pass interferometry. There is considerable interest internationally in other future L-band and lower frequency systems, as well. Therefore, the issues of prevalence and possibilities of mitigation of RFI in these crowded frequency bands are of considerable interest. RFI is observed in ALOS PALSAR in California and Hawaii, USA, and in southern Egypt in data examined to date. Application of several techniques for removing it from the data prior to SAR image formation, ranging from straight-forward spectral normalization to time-domain, multi-phase filtering techniques, are considered. Considerable experience has been gained from the removal of RFI from P-band acquired by the GeoSAR system. These techniques applied to the PALSAR data are most successful when the bandwidth of any particular spectral component of the RFI is narrow. Performance impacts for SAR imagery and interferograms are considered in the context of DESDynI measurement requirements.},
    ISSN = {1097-5659},
    Keywords = {DESDynI mission,L-band polarimetric radar;RFI;SAR data;radio frequency interference;synthetic aperture radar;radiofrequency interference;synthetic aperture radar} 
    }
    


  20. Stefano Tebaldini. Forest SAR tomography: A covariance matching approach. In IEEE Radar Conference, 2008. RADAR '08., pages 1-6, May 2008. Keyword(s): SAR Processing, SAR Tomography, Tomography, E-SAR, P-Band, radar imaging, radar interferometry, radar polarimetry, radar resolution, synthetic aperture radar, tomography, P-band SAR images, covariance matching approach, forest SAR tomography, multipolarimetric channel data, single polarimetric channel data, single target interferometric analysis, synthetic aperture radar interferometry, system resolution cell.
    Abstract: In this paper a technique to conduct tomographic analyses of forested areas through multiple, coherent SAR images is presented. This technique differs from other methods existing in literature in that it may be regarded as a natural extension of SAR interferometry to the case where several distributed targets are present within the system resolution cell. In this way, it is possible to estimate the position of each target in the resolution cell with virtually the same accuracy obtainable by a single target interferometric analysis. Furthermore, this approach is suited to both single and multi polarimetric channel data. As a validation, this paper reports the results of a tomographic analysis of the forest site of Remningstorp, Sweden, basing on a data-set of 9 P-band SAR images acquired by DLRpsilas E-SAR.

    @InProceedings{tebaldiniRADAR2008:Tomo,
    author = {Tebaldini, Stefano},
    booktitle = {IEEE Radar Conference, 2008. RADAR '08.},
    title = {Forest SAR tomography: A covariance matching approach},
    year = {2008},
    month = {may},
    pages = {1-6},
    abstract = {In this paper a technique to conduct tomographic analyses of forested areas through multiple, coherent SAR images is presented. This technique differs from other methods existing in literature in that it may be regarded as a natural extension of SAR interferometry to the case where several distributed targets are present within the system resolution cell. In this way, it is possible to estimate the position of each target in the resolution cell with virtually the same accuracy obtainable by a single target interferometric analysis. Furthermore, this approach is suited to both single and multi polarimetric channel data. As a validation, this paper reports the results of a tomographic analysis of the forest site of Remningstorp, Sweden, basing on a data-set of 9 P-band SAR images acquired by DLRpsilas E-SAR.},
    doi = {10.1109/RADAR.2008.4721084},
    issn = {1097-5659},
    keywords = {SAR Processing, SAR Tomography, Tomography, E-SAR, P-Band, radar imaging, radar interferometry, radar polarimetry, radar resolution, synthetic aperture radar, tomography, P-band SAR images, covariance matching approach, forest SAR tomography, multipolarimetric channel data, single polarimetric channel data, single target interferometric analysis, synthetic aperture radar interferometry, system resolution cell},
    owner = {ofrey},
    pdf = {../../../docs/tebaldiniRADAR2008.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4721084&isnumber=4720717&tag=1},
    
    }
    


  21. Stefano Tebaldini, Fabio Rocca, and A Monti-Guarnieri. Model Based SAR Tomography of Forested Areas. In IEEE International Geoscience and Remote Sensing Symposium, volume 2, pages 593-596, July 2008. Keyword(s): SAR Processing, SAR Tomography, Tomography, E-SAR, P-Band.
    Abstract: In this paper a technique is described for the tomographic characterization of forested areas through multiple SAR observations. This technique is based on a model of the second order statistics of the multi baseline, multi polarimetric, data which accounts for the presence of multiple distributed targets within the system resolution cell. The results of an experiment performed on a real P-band, multi-baseline, fully polarimetric data set relative to the forested site of Remningstorp, Sweden, are reported. Such results show the feasibility of performing a model based tomographic analysis of forests, resulting in a characterization of both the ground and the canopy in terms of elevation, spatial structure, and scattered power.

    @InProceedings{tebaldiniRoccaGuarnieri2008:Tomo,
    Title = {Model Based {SAR} Tomography of Forested Areas},
    Author = {Tebaldini, Stefano and Rocca, Fabio and Monti-Guarnieri, A},
    Booktitle = {IEEE International Geoscience and Remote Sensing Symposium},
    Doi = {10.1109/IGARSS.2008.4779062},
    Month = {jul},
    Pages = {593--596},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4779062&isnumber=4778902},
    Volume = {2},
    Year = {2008},
    Abstract = {In this paper a technique is described for the tomographic characterization of forested areas through multiple SAR observations. This technique is based on a model of the second order statistics of the multi baseline, multi polarimetric, data which accounts for the presence of multiple distributed targets within the system resolution cell. The results of an experiment performed on a real P-band, multi-baseline, fully polarimetric data set relative to the forested site of Remningstorp, Sweden, are reported. Such results show the feasibility of performing a model based tomographic analysis of forests, resulting in a characterization of both the ground and the canopy in terms of elevation, spatial structure, and scattered power.},
    Keywords = {SAR Processing, SAR Tomography, Tomography, E-SAR, P-Band},
    Owner = {ofrey},
    Pdf = {../../../docs/tebaldiniRoccaGuarnieri2008.pdf} 
    }
    


  22. Daniel E. Wahl, David A. Yocky, and Charles V. Jakowatz. An implementation of a fast backprojection image formation algorithm for spotlight-mode SAR. In Edmund G. Zelnio and Frederick D. Garber, editors, , volume 6970, pages 69700H, 2008. SPIE. Keyword(s): SAR Processing, Back-projection, Time-Domain Back-Projection, TDBP, Fast Back-projection, Fast Factorized Back-Projection, FFBP, Spotlight SAR, Spotlight-mode data.
    @Conference{wahlYockyJakowatzFastBackprojectionSpotlight2008,
    author = {Daniel E. Wahl and David A. Yocky and Charles V. Jakowatz, Jr.},
    title = {An implementation of a fast backprojection image formation algorithm for spotlight-mode {SAR}},
    year = {2008},
    editor = {Edmund G. Zelnio and Frederick D. Garber},
    volume = {6970},
    number = {1},
    pages = {69700H},
    publisher = {SPIE},
    doi = {10.1117/12.779401},
    eid = {69700H},
    file = {:wahlYockyJakowatzFastBackprojectionSpotlight2008.pdf:PDF},
    journal = {Algorithms for Synthetic Aperture Radar Imagery XV},
    keywords = {SAR Processing, Back-projection, Time-Domain Back-Projection, TDBP, Fast Back-projection, Fast Factorized Back-Projection, FFBP, Spotlight SAR, Spotlight-mode data},
    location = {Orlando, FL, USA},
    numpages = {11},
    owner = {ofrey},
    pdf = {../../../docs/wahlYockyJakowatzFastBackprojectionSpotlight2008.pdf},
    url = {http://link.aip.org/link/?PSI/6970/69700H/1},
    
    }
    


  23. Yanping Wang, Bin Wang, Wen Hong, Lei Du, and Yirong Wu. Imaging Geometry Analysis of 3D SAR using Linear Array Antennas. In IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2008, volume 3, pages 1216-1219, July 2008. Keyword(s): SAR Processing, SAR Tomography, Tomography, linear antenna arrays, radar imaging, radar interferometry, synthetic aperture radar, 3D SAR, elevation direction, imaging geometry analysis, linear array antennas, signal model.
    Abstract: Linear array antennas SAR has a resolving capability in the elevation direction, and can get the 3D image of the target. In this paper, we derive the signal model of 3D SAR using a linear array antenna, and get the 3D resolutions and 3D point spread function of array antenna SAR, at the same time the sampling space of array antennas is given. The variance of the resolution in the elevation direction with array antenna angle and referenced look angle is studied. The geometry to reach the best resolution in the elevation direction is analyzed. Meanwhile the resolution for horizontal and vertical antenna array are calculated and compared.

    @InProceedings{wangWangHongDuWu2008:SARTom,
    Title = {{Imaging Geometry Analysis of 3D SAR using Linear Array Antennas}},
    Author = {Yanping Wang and Bin Wang and Wen Hong and Lei Du and Yirong Wu},
    Booktitle = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2008},
    Doi = {10.1109/IGARSS.2008.4779576},
    Month = {jul},
    Pages = {1216-1219},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4779576&isnumber=4779256},
    Volume = {3},
    Year = {2008},
    Abstract = {Linear array antennas SAR has a resolving capability in the elevation direction, and can get the 3D image of the target. In this paper, we derive the signal model of 3D SAR using a linear array antenna, and get the 3D resolutions and 3D point spread function of array antenna SAR, at the same time the sampling space of array antennas is given. The variance of the resolution in the elevation direction with array antenna angle and referenced look angle is studied. The geometry to reach the best resolution in the elevation direction is analyzed. Meanwhile the resolution for horizontal and vertical antenna array are calculated and compared.},
    Keywords = {SAR Processing, SAR Tomography, Tomography, linear antenna arrays, radar imaging, radar interferometry, synthetic aperture radar, 3D SAR, elevation direction, imaging geometry analysis, linear array antennas, signal model},
    Owner = {ofrey},
    Pdf = {../../../docs/wangWangHongDuWu2008.pdf} 
    }
    


  24. Charles L. Werner, Tazio Strozzi, Andreas Wiesmann, and Urs Wegmuller. A Real-Aperture Radar for Ground-Based Differential Interferometry. In Proc. IEEE Int. Geosci. Remote Sens. Symp., volume 3, pages 210-213, July 2008. Keyword(s): SAR Processing, Antenna measurements, Instruments, Interferometry, Monitoring, Radar antennas, Radar imaging, Receiving antennas, Satellites, Spaceborne radar, Terrain factors, antennas, geomorphology, geophysical equipment, radar interferometry, remote sensing by radar, rocks, spaceborne radar, synthetic aperture radar, GAMMA Portable Radar Interferometer, GPRI, frequency 17.2 GHz, ground-based differential interferometry, height measurements, image acquisition, in-situ radar imaging system, landslides, line-of-sight displacements, phase differences, photogrammetry systems, real-aperture radar, receiving antennas, rock fall warning system, slope stability, space-borne INSAR, space-borne SAR interferometry, surface topography, GAMMA, RAR, Radar Interferometer, glacier, landslide;.
    Abstract: Satellite interferometry has been used extensively for ground-motion monitoring with good success. In the case of landslides, for example, space-borne SAR interferometry has a good potential to get an overview on the slope stability. The role of a space-borne INSAR as an element in a landslide or rock fall warning system is constrained by the specific space-borne SAR imaging geometry, the typical multiple-week repeat-interval, and uncertainties in the data availability. Most of these limitations can be overcome with an in-situ radar imaging system. GAMMA has developed a portable radar interferometer that utilizes real-aperture antennas to obtain high azimuth resolution. Images are acquired line by line while rotating the transmitting and receiving antennas about a vertical axis. Phase differences between successive images acquired from the same location are used to determine line-of-sight displacements. The instrument operates at 17.2 GHz and has measurement sensitivity better than 1 mm. The instrument uses two receiving antennas with a short baseline to form an interferometer. Phase differences between simultaneous acquisitions by these antennas are used to calculate the precise look angle relative to the baseline, permitting derivation of the surface topography. Expected statistical noise in the height measurements is on the order of 1 meter. In this contribution the design, measurement principles and characteristics of GAMMA's Portable Radar Interferometer (GPRI) are presented.

    @InProceedings{wernerStrozziWiesmannWegmullerIGARSS2008GPRI,
    author = {Werner, Charles L. and Strozzi, Tazio and Wiesmann, Andreas and Wegmuller, Urs},
    title = {A Real-Aperture Radar for Ground-Based Differential Interferometry},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2008},
    volume = {3},
    pages = {210-213},
    month = jul,
    abstract = {Satellite interferometry has been used extensively for ground-motion monitoring with good success. In the case of landslides, for example, space-borne SAR interferometry has a good potential to get an overview on the slope stability. The role of a space-borne INSAR as an element in a landslide or rock fall warning system is constrained by the specific space-borne SAR imaging geometry, the typical multiple-week repeat-interval, and uncertainties in the data availability. Most of these limitations can be overcome with an in-situ radar imaging system. GAMMA has developed a portable radar interferometer that utilizes real-aperture antennas to obtain high azimuth resolution. Images are acquired line by line while rotating the transmitting and receiving antennas about a vertical axis. Phase differences between successive images acquired from the same location are used to determine line-of-sight displacements. The instrument operates at 17.2 GHz and has measurement sensitivity better than 1 mm. The instrument uses two receiving antennas with a short baseline to form an interferometer. Phase differences between simultaneous acquisitions by these antennas are used to calculate the precise look angle relative to the baseline, permitting derivation of the surface topography. Expected statistical noise in the height measurements is on the order of 1 meter. In this contribution the design, measurement principles and characteristics of GAMMA's Portable Radar Interferometer (GPRI) are presented.},
    doi = {10.1109/IGARSS.2008.4779320},
    file = {:wernerStrozziWiesmannWegmullerIGARSS2008GPRI.pdf:PDF},
    keywords = {SAR Processing, Antenna measurements;Instruments;Interferometry;Monitoring;Radar antennas;Radar imaging;Receiving antennas;Satellites;Spaceborne radar;Terrain factors;antennas;geomorphology;geophysical equipment;radar interferometry;remote sensing by radar;rocks;spaceborne radar;synthetic aperture radar;GAMMA Portable Radar Interferometer;GPRI;frequency 17.2 GHz;ground-based differential interferometry;height measurements;image acquisition;in-situ radar imaging system;landslides;line-of-sight displacements;phase differences;photogrammetry systems;real-aperture radar;receiving antennas;rock fall warning system;slope stability;space-borne INSAR;space-borne SAR interferometry;surface topography;GAMMA;RAR;Radar Interferometer;glacier;landslide;},
    pdf = {../../../docs/wernerStrozziWiesmannWegmullerIGARSS2008GPRI.pdf},
    
    }
    


  25. Andreas Wiesmann, Charles L. Werner, Christian Matzler, Martin Schneebeli, Tazio Strozzi, and Urs Wegmuller. Mobile X- to Ku-band Scatterometer in Support of the CoRe-H2O Mission. In Proc. IEEE Int. Geosci. Remote Sens. Symp., volume 5, pages 244-247, July 2008. Keyword(s): SnowScat, KuScat, backscatter, hydrological techniques, radiometry, remote sensing by radar, snow, spaceborne radar, C-band SAR satellite systems, ESA CoRe-H2O mission, Ku-band scatterometer, Swiss Alps, X-band scatterometer, backscatter information, backscattering signal, dry snow cover, dual frequency radar, frequency 18 GHz, frequency 9 GHz, mobile scatterometer, snow coverage, snow liquid water content, snow structure, spaceborne active microwave remote sensing, Backscatter, Frequency, Ground support, Radar measurements, Remote sensing, Satellites, Signal generators, Snow, Spaceborne radar, Water storage, Scatterometer, Snow, backscatter, snow grain.
    Abstract: Information on snow coverage, structure, and liquid water content are important for many applications including avalanche warning, numerical weather prognosis (NWP), and snow pack water storage estimate. Active microwave remote sensing from space has an excellent potential to address these needs. However, the current generation of C-band SAR satellite systems are not well suited for snow related applications because of the small impact of the dry snow cover on the backscattering signal at 5.3 GHz. In order to be more sensitive to snow properties the envisaged ESA CoReH2O mission proposes a dual-frequency radar operating at 9 and 18 GHz (X- and Ku-band). In support of this mission, a ground based 9 to 18 GHz scatterometer is being developed to help to address the lack of simultaneous backscatter information of snow in this frequency range. We are also preparing a dedicated field campaign in the Swiss Alps to evaluate the performance of the system and acquire first data.

    @InProceedings{wiesmannWernerMatzlerSchneebeliStrozziWegmullerIGARSS2008SnowScat,
    author = {Wiesmann, Andreas and Werner, Charles L. and Matzler, Christian and Schneebeli, Martin and Strozzi, Tazio and Wegmuller, Urs},
    title = {Mobile {X-} to {Ku-}band Scatterometer in Support of the {CoRe-H2O} Mission},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2008},
    volume = {5},
    pages = {244-247},
    month = jul,
    abstract = {Information on snow coverage, structure, and liquid water content are important for many applications including avalanche warning, numerical weather prognosis (NWP), and snow pack water storage estimate. Active microwave remote sensing from space has an excellent potential to address these needs. However, the current generation of C-band SAR satellite systems are not well suited for snow related applications because of the small impact of the dry snow cover on the backscattering signal at 5.3 GHz. In order to be more sensitive to snow properties the envisaged ESA CoReH2O mission proposes a dual-frequency radar operating at 9 and 18 GHz (X- and Ku-band). In support of this mission, a ground based 9 to 18 GHz scatterometer is being developed to help to address the lack of simultaneous backscatter information of snow in this frequency range. We are also preparing a dedicated field campaign in the Swiss Alps to evaluate the performance of the system and acquire first data.},
    doi = {10.1109/IGARSS.2008.4780073},
    file = {:wiesmannWernerMatzlerSchneebeliStrozziWegmullerIGARSS2008SnowScat.pdf:PDF},
    keywords = {SnowScat, KuScat, backscatter;hydrological techniques;radiometry;remote sensing by radar;snow;spaceborne radar;C-band SAR satellite systems;ESA CoRe-H2O mission;Ku-band scatterometer;Swiss Alps;X-band scatterometer;backscatter information;backscattering signal;dry snow cover;dual frequency radar;frequency 18 GHz;frequency 9 GHz;mobile scatterometer;snow coverage;snow liquid water content;snow structure;spaceborne active microwave remote sensing;Backscatter;Frequency;Ground support;Radar measurements;Remote sensing;Satellites;Signal generators;Snow;Spaceborne radar;Water storage;Scatterometer;Snow;backscatter;snow grain},
    
    }
    


  26. E.C. Zaugg and D.G. Long. Along-Track Resolution Enhancement Forwide-Bandwidth, Low-Frequency SAR by Accounting for the Wavelength Change over the Bandwidth. In Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International, volume 4, pages 1272-1275, July 2008. Keyword(s): SAR Processing.
    @InProceedings{Zaugg2008,
    Title = {Along-Track Resolution Enhancement Forwide-Bandwidth, Low-Frequency SAR by Accounting for the Wavelength Change over the Bandwidth},
    Author = {Zaugg, E.C. and Long, D.G.},
    Booktitle = {Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International},
    Doi = {10.1109/IGARSS.2008.4779962},
    Month = jul,
    Pages = {1272--1275},
    Volume = {4},
    Year = {2008},
    Keywords = {SAR Processing},
    Owner = {ofrey} 
    }
    


Internal reports

  1. Candidate Earth Explorer Core Mission BIOMASS - Report for Assessment. Technical report, ESA SP-1313/2, November 2008. Keyword(s): BIOMASS mission, Earth explorer core mission candidate, P-band, forest area, forest biomass, forest disturbances, frequency 425 MHz, global maps, synthetic aperture radar, terrestrial carbon cycle, remote sensing by radar, spaceborne radar, synthetic aperture radar.
    @TechReport{BIOMASS_ESA_EARTH_EXPLORER_MISSION2008,
    Title = {Candidate {Earth} Explorer Core Mission {BIOMASS} - Report for Assessment},
    Month = nov,
    Url = {http://esamultimedia.esa.int/docs/SP1313-2_BIOMASS.pdf},
    Year = {2008},
    Address = {ESA SP-1313/2},
    Keywords = {BIOMASS mission;Earth explorer core mission candidate;P-band; forest area;forest biomass;forest disturbances;frequency 425 MHz; global maps;synthetic aperture radar;terrestrial carbon cycle; remote sensing by radar;spaceborne radar;synthetic aperture radar} 
    }
    


Miscellaneous

  1. Andreas Reigber. Multimodale Verarbeitung hochauflösender SAR Daten, February 2008. Note: Habilitationsschrift an der Fakultät IV -Elektrotechnik un Informatik - der Technischen Universität Berlin. Keyword(s): SAR Processing, airborne SAR, omega-k, Range Migration Algorithm, Wave Number Domain Algorithm, Extended Chirp Scaling, ECS, SAR Interferometry, Interferometry, InSAR, Residual Motion Errors, Residual Errors, Motion Compensation, MoComp, PolInSAR, Polarimetry.
    Abstract: Abbildende Radartechnik ist ein Fernerkundungsverfahren, welches das Ziel hat, von einer beobachteten Gegend eine hochaufgel\"oste Reflektivit\"atskarte im Mikrowellenbereich zu erzeugen. Erreicht wird dies durch Abstrahlung und Empfang von elektromagnetischer Strahlung im Mikrowellenbereich, typischerweise durch Sensoren, die auf Flugzeugen oder Satelliten montiert sind. Unter einer ganzen Reihe von Mikrowellensensoren hat sich in den letzten Jahren ein besonderes Interesse in Radar mit synthetischer Apertur (SAR) herausgebildet. Der Grund hierf\"ur ist, dass das SAR als einziger Mikrowellensensor eine fl\"achige Abbildung mit einer hohen r\"aumlichen Aufl\"osung, die durchaus mit der optischer Systeme vergleichbar ist, erm\"oglicht. Die Entwicklungsgeschichte des Radars mit synthetischer Apertur begann bereits vor \"uber 50 Jahren mit der Idee, die Doppler-Verschiebung des Radarsignals zu nutzen, um die Azimutaufl\"osung des damals aktuellen side-looking airborne radar (SLAR) zu verbessern [215]. Zur Prozessierung der Daten war man, bis in die 1970er Jahre hinein, auf die Verwendung optischer, holographischer Verfahren angewiesen; erst danach war man in der Lage, mittels digitaler Datenverarbeitung hochaufgel\"oste SAR Aufnahmen in hoher Qualit\"at zu erzeugen [10],[216]. Seitdem entwickelte sich die Fernerkundung mit SAR Sensoren rasant weiter, hin zu immer h\"oheren Aufl\"osungen und Aufnahmemodi. In den letzten 10 Jahren gewannen dabei vor allem die mehrkanalige SAR Modi stark an Bedeutung, wie z.B. multispektrales SAR [66], SAR Interferometrie [8] und SAR Polarimetrie [13]. Diese Arbeit besch\"aftigt sich vor allem mit speziellen Datenverarbeitungstechniken solcher mehrkanaliger SAR Daten. SAR Sensoren arbeiten im Mikrowellenbereich des elektromagnetischen Spektrums bei Wellenl\"angen zwischen wenigen Millimetern und mehreren Metern. Betrachtet man das Transmissionsspektrum der Erdatmosph\"are, so stellt man fest, dass bei Wellenl\"angen gr\"osser als etwa 1cm praktisch keine nennenswerte Absorption mehr auftritt. Dies gilt sowohl f\"ur die Luft selbst als auch f\"ur Wolken und kleinere Wassertropfen. SAR Aufnahmen lassen sich daher praktisch unabh\"angig von den aktuell herrschenden Wetterbedingungen generieren, wohingegen Wolken und Nebel f\"ur optische Systeme oft eine grosse Einschr\"ankung darstellen. Als aktives System, das seine eigene Beleuchtung mitbringt, besteht weiterhin keinerlei Abh\"angigkeit von der jeweiligen Tageszeit. Zusammengenommen f\"uhren diese Punkte dazu, dass sich SAR Sensoren besonders gut f\"ur verl\"assliche und regelm\"assige Beobachtungen eignen. Der Informationsgehalt von Radaraufnahmen ist deutlich anders gelagert als der von optischen oder Infrarotsystemen. W\"ahrend im optischen Bereich vor allem die molekulare Zusammensetzung des Objekts f\"ur die charakteristische Reflektivit\"at des Objekts verantwortlich zeichnet, sind im Mikrowellenbereich vor allem die geometrische Form sowie die dielektrischen Eigenschaften f\"ur die St\"arke der R\"uckstreuung von Bedeutung. In Radaraufnahmen tritt daher das Relief und morphologische Strukturen besonders deutlich hervor. Auch \"Anderungen in der Leitf\"ahigkeit, z.B. durch unterschiedliche Bodenfeuchte, k\"onnen so beobachtet werden. Aufgrund der Sensitivit \"at auf dielektrische Eigenschaften k\"onnen im Prinzip sogar Informationen \"uber den Vegetationszustand gesammelt werden.

    @Misc{ReigberHabil2008:MultimodalSAR,
    author = {Andreas Reigber},
    month = feb,
    note = {Habilitationsschrift an der Fakult\"at IV -Elektrotechnik un Informatik - der Technischen Universit\"at Berlin},
    title = {Multimodale Verarbeitung hochaufl\"osender SAR Daten},
    year = {2008},
    abstract = {Abbildende Radartechnik ist ein Fernerkundungsverfahren, welches das Ziel hat, von einer beobachteten Gegend eine hochaufgel\"oste Reflektivit\"atskarte im Mikrowellenbereich zu erzeugen. Erreicht wird dies durch Abstrahlung und Empfang von elektromagnetischer Strahlung im Mikrowellenbereich, typischerweise durch Sensoren, die auf Flugzeugen oder Satelliten montiert sind. Unter einer ganzen Reihe von Mikrowellensensoren hat sich in den letzten Jahren ein besonderes Interesse in Radar mit synthetischer Apertur (SAR) herausgebildet. Der Grund hierf\"ur ist, dass das SAR als einziger Mikrowellensensor eine fl\"achige Abbildung mit einer hohen r\"aumlichen Aufl\"osung, die durchaus mit der optischer Systeme vergleichbar ist, erm\"oglicht. Die Entwicklungsgeschichte des Radars mit synthetischer Apertur begann bereits vor \"uber 50 Jahren mit der Idee, die Doppler-Verschiebung des Radarsignals zu nutzen, um die Azimutaufl\"osung des damals aktuellen side-looking airborne radar (SLAR) zu verbessern [215]. Zur Prozessierung der Daten war man, bis in die 1970er Jahre hinein, auf die Verwendung optischer, holographischer Verfahren angewiesen; erst danach war man in der Lage, mittels digitaler Datenverarbeitung hochaufgel\"oste SAR Aufnahmen in hoher Qualit\"at zu erzeugen [10],[216]. Seitdem entwickelte sich die Fernerkundung mit SAR Sensoren rasant weiter, hin zu immer h\"oheren Aufl\"osungen und Aufnahmemodi. In den letzten 10 Jahren gewannen dabei vor allem die mehrkanalige SAR Modi stark an Bedeutung, wie z.B. multispektrales SAR [66], SAR Interferometrie [8] und SAR Polarimetrie [13]. Diese Arbeit besch\"aftigt sich vor allem mit speziellen Datenverarbeitungstechniken solcher mehrkanaliger SAR Daten. SAR Sensoren arbeiten im Mikrowellenbereich des elektromagnetischen Spektrums bei Wellenl\"angen zwischen wenigen Millimetern und mehreren Metern. Betrachtet man das Transmissionsspektrum der Erdatmosph\"are, so stellt man fest, dass bei Wellenl\"angen gr\"osser als etwa 1cm praktisch keine nennenswerte Absorption mehr auftritt. Dies gilt sowohl f\"ur die Luft selbst als auch f\"ur Wolken und kleinere Wassertropfen. SAR Aufnahmen lassen sich daher praktisch unabh\"angig von den aktuell herrschenden Wetterbedingungen generieren, wohingegen Wolken und Nebel f\"ur optische Systeme oft eine grosse Einschr\"ankung darstellen. Als aktives System, das seine eigene Beleuchtung mitbringt, besteht weiterhin keinerlei Abh\"angigkeit von der jeweiligen Tageszeit. Zusammengenommen f\"uhren diese Punkte dazu, dass sich SAR Sensoren besonders gut f\"ur verl\"assliche und regelm\"assige Beobachtungen eignen. Der Informationsgehalt von Radaraufnahmen ist deutlich anders gelagert als der von optischen oder Infrarotsystemen. W\"ahrend im optischen Bereich vor allem die molekulare Zusammensetzung des Objekts f\"ur die charakteristische Reflektivit\"at des Objekts verantwortlich zeichnet, sind im Mikrowellenbereich vor allem die geometrische Form sowie die dielektrischen Eigenschaften f\"ur die St\"arke der R\"uckstreuung von Bedeutung. In Radaraufnahmen tritt daher das Relief und morphologische Strukturen besonders deutlich hervor. Auch \"Anderungen in der Leitf\"ahigkeit, z.B. durch unterschiedliche Bodenfeuchte, k\"onnen so beobachtet werden. Aufgrund der Sensitivit \"at auf dielektrische Eigenschaften k\"onnen im Prinzip sogar Informationen \"uber den Vegetationszustand gesammelt werden.},
    address = {Technische Universit\"at Berlin},
    keywords = {SAR Processing, airborne SAR, omega-k, Range Migration Algorithm, Wave Number Domain Algorithm, Extended Chirp Scaling, ECS, SAR Interferometry, Interferometry, InSAR, Residual Motion Errors, Residual Errors, Motion Compensation, MoComp, PolInSAR, Polarimetry},
    owner = {ofrey},
    pdf = {../../../docs/ReigberHabil2008.pdf},
    url = {http://elib.dlr.de/54771/01/reigber_habil.pdf},
    
    }
    


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Please note that access to full text PDF versions of papers is restricted to the Chair of Earth Observation and Remote Sensing, Institute of Environmental Engineering, ETH Zurich.
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This collection of SAR literature is far from being complete.
It is rather a collection of papers which I store in my literature data base. Hence, the list of publications under PUBLICATIONS OF AUTHOR'S NAME should NOT be mistaken for a complete bibliography of that author.




Last modified: Mon Feb 1 16:39:00 2021
Author: Othmar Frey, Earth Observation and Remote Sensing, Institute of Environmental Engineering, Swiss Federal Institute of Technology - ETH Zurich .


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