BACK TO INDEX BACK TO OTHMAR FREY'S HOMEPAGE

Publications of year 2000

Thesis

  1. Richard T. Lord. Aspects of Stepped-Frequency Processing for Low-Frequency SAR Systems. PhD thesis, University of Cape Town, Rondebosch, South Africa, 2000. Keyword(s): SAR Processing, Stepped-Frequency Processing, RFI Suppression, Low-Frequency SAR, Wideband SAR.
    Abstract: Ultra-wideband synthetic aperture radar (SAR) systems operating in the VHF/UHF region are becoming increasingly popular because of their growing number of applications in the areas of foliage penetration radar (FOPEN) and ground-penetrating radar (GPR). The objective of this thesis is to investigate the following two aspects of low-frequency (VHF/UHF-band) SAR processing: 1. The use of stepped-frequency waveforms to increase the total radar bandwidth, thereby increasing the range resolution, and 2. Radio frequency interference (RFI) suppression. A stepped-frequency system owes its wide bandwidth to the transmission of a group of narrow-bandwidth pulses, which are then combined using a signal processing technique to achieve the wide bandwidth. Apart from providing an economically viable path for the upgrading of an existing single frequency system, stepped-frequency waveforms also offer opportunities for RFI suppression. This thesis describes three methods to process stepped-frequency waveforms, namely an IFFTmethod, a time-domainmethod and a frequency-domainmethod. Both the IFFT method and the time-domain method have been found to be unsuitable for SAR processing applications. The IFFT method produces multiple ghost targets in the high resolution range profile due to the spill-over effect of energy into consecutive coarse range bins, and the time-domain technique is computationally inefficient on account of the upsampling requirement of the narrow-bandwidth pulses prior to the frequency shift. The frequency-domain technique, however, efficiently uses all the information in the narrowband pulses to obtain high-resolution range profiles which do not contain any ghost targets, and is therefore well suited for SAR processing applications. This technique involves the reconstruction of a wider portion of the target\u2019s reflectivity spectrum by combining the individual spectra of the transmitted narrow-bandwidth pulses in the frequency domain. It is shown here how this method may be used to avoid spectral regions that are heavily contaminated with RFI, thereby alleviating the problem of receiver saturation due to RFI. Stepped-frequency waveforms also enable the A/D converter to sample the received narrow-bandwidth waveform with a larger number of bits, which increases the receiver dynamic range, thereby further alleviating the problem of receiver saturation during the presence of RFI. In addition to using stepped-frequency waveforms for RFI suppression, a number of other techniques have been investigated to suppress RFI... Of these, the notch filter and the LMS adaptive filter have been implemented and applied on real P-band data obtained from the E-SAR system of the German Aerospace Center (DLR), Oberpfaffenhofen, and on real VHF-band data obtained from the South African SAR (SASAR) system. Both methods significantly suppressed the RFI in the real images investigated. It was found that the number of range lines upon which the LMS adaptive filter could operate without adaptively changing the filter tap weights was often well above 100. This facilitated the re-writing of the LMS adaptive filter in terms of an equivalent transfer function, which was then integrated with the range-compression stage of the range-Doppler SAR processing algorithm. Since the range-compression and the interference suppression could then be performed simultaneously, large computational savings were achieved. A technique was derived for suppressing the sidelobes which arise as a result of the interference suppression of the LMS adaptive filter. This method was also integrated with the range-compression stage of the range-Doppler processor, leading to a very efficient implementation of the entire RFI suppression routine.
    Comments: +Frequency/time/IFFT processing of stepped frequencies and applications toward radio frequency interferences (RFI).

    @PhdThesis{LordDissertation00:SteppedFreqAndRFI,
    Title = {{Aspects of Stepped-Frequency Processing for Low-Frequency SAR Systems }},
    Author = {Richard T. Lord},
    Year = {2000},
    Abstract = {Ultra-wideband synthetic aperture radar (SAR) systems operating in the VHF/UHF region are becoming increasingly popular because of their growing number of applications in the areas of foliage penetration radar (FOPEN) and ground-penetrating radar (GPR). The objective of this thesis is to investigate the following two aspects of low-frequency (VHF/UHF-band) SAR processing: 1. The use of stepped-frequency waveforms to increase the total radar bandwidth, thereby increasing the range resolution, and 2. Radio frequency interference (RFI) suppression. A stepped-frequency system owes its wide bandwidth to the transmission of a group of narrow-bandwidth pulses, which are then combined using a signal processing technique to achieve the wide bandwidth. Apart from providing an economically viable path for the upgrading of an existing single frequency system, stepped-frequency waveforms also offer opportunities for RFI suppression. This thesis describes three methods to process stepped-frequency waveforms, namely an IFFTmethod, a time-domainmethod and a frequency-domainmethod. Both the IFFT method and the time-domain method have been found to be unsuitable for SAR processing applications. The IFFT method produces multiple ghost targets in the high resolution range profile due to the spill-over effect of energy into consecutive coarse range bins, and the time-domain technique is computationally inefficient on account of the upsampling requirement of the narrow-bandwidth pulses prior to the frequency shift. The frequency-domain technique, however, efficiently uses all the information in the narrowband pulses to obtain high-resolution range profiles which do not contain any ghost targets, and is therefore well suited for SAR processing applications. This technique involves the reconstruction of a wider portion of the target\u2019s reflectivity spectrum by combining the individual spectra of the transmitted narrow-bandwidth pulses in the frequency domain. It is shown here how this method may be used to avoid spectral regions that are heavily contaminated with RFI, thereby alleviating the problem of receiver saturation due to RFI. Stepped-frequency waveforms also enable the A/D converter to sample the received narrow-bandwidth waveform with a larger number of bits, which increases the receiver dynamic range, thereby further alleviating the problem of receiver saturation during the presence of RFI. In addition to using stepped-frequency waveforms for RFI suppression, a number of other techniques have been investigated to suppress RFI... Of these, the notch filter and the LMS adaptive filter have been implemented and applied on real P-band data obtained from the E-SAR system of the German Aerospace Center (DLR), Oberpfaffenhofen, and on real VHF-band data obtained from the South African SAR (SASAR) system. Both methods significantly suppressed the RFI in the real images investigated. It was found that the number of range lines upon which the LMS adaptive filter could operate without adaptively changing the filter tap weights was often well above 100. This facilitated the re-writing of the LMS adaptive filter in terms of an equivalent transfer function, which was then integrated with the range-compression stage of the range-Doppler SAR processing algorithm. Since the range-compression and the interference suppression could then be performed simultaneously, large computational savings were achieved. A technique was derived for suppressing the sidelobes which arise as a result of the interference suppression of the LMS adaptive filter. This method was also integrated with the range-compression stage of the range-Doppler processor, leading to a very efficient implementation of the entire RFI suppression routine.},
    Address = {Rondebosch, South Africa},
    Comments = {+Frequency/time/IFFT processing of stepped frequencies and applications toward radio frequency interferences (RFI).},
    Keyword = {SAR Processing, Stepped-Frequency Processing, RFI Suppression, Low-Frequency SAR, Wideband SAR},
    Pdf = {../../../docs/LordDissertation00.pdf},
    Publisher = {University of Cape Town},
    School = {University of Cape Town} 
    }
    


  2. Josef Mittermayer. Hochauflösende Verarbeitung von Radardaten mit synthetischer Apertur. PhD thesis, Universität-Gesamthochschule Siegen, 2000. Keyword(s): SAR Processing, Frequency Scaling Algorithm, Comparison of Algorithms, Range-Doppler Algorithm, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm, Polar Format Algorithm, SPECAN, Convolution Back-projection, Spotlight SAR, Stripmap SAR, ScanSAR, ESAR, Airborne SAR, Spaceborne SAR.
    Abstract: In this thesis, the novel Frequency Scaling Algorithm for efficient and accurate interpolation-free processing of Spotlight SAR data with Dechirp on Receive has been developed. An accurate analytical model of the Spotlight illumination geometry for a straight flight path of the carrier is introduced. Using this model, a valid and an illuminated target area is defined. A new analytical formulation for SAR raw data with one-dimensional Dechirp on Receive Operation is derived, which expresses the Residual Video Phase Term by a convolution with a chirp signal. Starting with this formulation, an interpolation-free range cell migration correction is developed. This range cell migration correction is called Frequency Scaling. Due to the constant target illumination start and end time in Spotlight SAR data, the SPECAN approach offers a very efficient processing in azimuth but due to the poor accuracy, it has only been used for ScanSAR and not for Spotlight data up to now. Furthermore, a SPECAN approach always requires interpolations. In the frame of this thesis, an azimuth scaling operation has been developed, which allows a highly accurate and interpolation-free processing of Spotlight data by the SPECAN approach. The combination of SPECAN approach and azimuth scaling is first applied to ScanSAR data in order to improve the Extended Chirp Scaling Algorithm. Then it is extended to Spotlight processing. Spotlight raw data with one-dimensional Dechirp on Receive have to be upsampled in azimuth before the data processing. In order to avoid this upsampling, a subaperture approach is introduced, which reduces the required azimuth sampling during the processing down to the pulse repetition frequency of the raw data. The high quality performance of the Frequency Scaling Algorithm is demonstrated by processing simulated and real raw data acquired with the E-SAR-Sensor of DLR. The phase fidelity, which is important for many applications, is proved by point target processing and by the generation of an interferogram of an E-SAR scene. As application example, a spotlight interferogram is generated from E-SAR raw data. Interesting physical properties of the Spotlight mode are demonstrated by the comparison of a Spotlight and a Stripmap interferogram, processed from the same raw data.

    @PhdThesis{mittermayer:sar,
    Title = {{Hochaufl\"osende Verarbeitung von Radardaten mit synthetischer Apertur}},
    Author = {Josef Mittermayer},
    Url = {http://www.ub.uni-siegen.de/pub/diss/fb12/2000/mittermayer/mittermayer.pdf},
    Year = {2000},
    Abstract = {In this thesis, the novel Frequency Scaling Algorithm for efficient and accurate interpolation-free processing of Spotlight SAR data with Dechirp on Receive has been developed. An accurate analytical model of the Spotlight illumination geometry for a straight flight path of the carrier is introduced. Using this model, a valid and an illuminated target area is defined. A new analytical formulation for SAR raw data with one-dimensional Dechirp on Receive Operation is derived, which expresses the Residual Video Phase Term by a convolution with a chirp signal. Starting with this formulation, an interpolation-free range cell migration correction is developed. This range cell migration correction is called Frequency Scaling. Due to the constant target illumination start and end time in Spotlight SAR data, the SPECAN approach offers a very efficient processing in azimuth but due to the poor accuracy, it has only been used for ScanSAR and not for Spotlight data up to now. Furthermore, a SPECAN approach always requires interpolations. In the frame of this thesis, an azimuth scaling operation has been developed, which allows a highly accurate and interpolation-free processing of Spotlight data by the SPECAN approach. The combination of SPECAN approach and azimuth scaling is first applied to ScanSAR data in order to improve the Extended Chirp Scaling Algorithm. Then it is extended to Spotlight processing. Spotlight raw data with one-dimensional Dechirp on Receive have to be upsampled in azimuth before the data processing. In order to avoid this upsampling, a subaperture approach is introduced, which reduces the required azimuth sampling during the processing down to the pulse repetition frequency of the raw data. The high quality performance of the Frequency Scaling Algorithm is demonstrated by processing simulated and real raw data acquired with the E-SAR-Sensor of DLR. The phase fidelity, which is important for many applications, is proved by point target processing and by the generation of an interferogram of an E-SAR scene. As application example, a spotlight interferogram is generated from E-SAR raw data. Interesting physical properties of the Spotlight mode are demonstrated by the comparison of a Spotlight and a Stripmap interferogram, processed from the same raw data.},
    Keywords = {SAR Processing, Frequency Scaling Algorithm, Comparison of Algorithms, Range-Doppler Algorithm, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm, Polar Format Algorithm, SPECAN, Convolution Back-projection, Spotlight SAR, Stripmap SAR, ScanSAR, ESAR, Airborne SAR, Spaceborne SAR},
    Pdf = {../../../docs/mittermayer_phd.pdf},
    School = {Universit\"at-Gesamthochschule Siegen} 
    }
    


Articles in journal or book chapters

  1. Falk Amelung, Sigurjon Jonsson, Howard Zebker, and Paul Segall. Widespread uplift and trapdoor faulting on Galapagos volcanoes observed with radar interferometry. Nature, 407(6807):993-996, October 2000. Keyword(s): SAR Processing, Interferometry, SAR interferometry, differential SAR interferometry, DInSAR, Deformation Mapping, Deformation Monitoring, ERS-1, ERS-2, Displacement, Surface Displacement, Surface Deformation, Spaceborne SAR, C-band, Volcano, Galapagos, deflation, Galapagos Islands, Cerro Azul, Fernandina, co-eruptive deflation, deflation, dyke intrusion.
    Abstract: Volcanic uplift, caused by the accumulation of magma in subsurface reservoirs, is a common precursor to eruptions. But, for some volcanoes, uplift of metres or more has not yet led to an eruption. Here we present displacement maps of volcanoes in the Galapagos Islands, constructed using satellite radar interferometry, that might help explain this dichotomy. We show that all but one of the seven volcanoes on the islands of Isabela and Fernandina deformed during 1992-99. Cerro Azul and Fernandina erupted during the observation period and show evidence of inflation, co-eruptive deflation and shallow dyke intrusion. In contrast, the largest volcano, Sierra Negra, has not erupted, yet exhibits spatially and temporally variable deformation, with a maximum uplift of 2.7 m between 1992 and 1999, which can be modelled by a shallow inflating sill. Inflation during 1997-98, however, was accompanied by 'trapdoor' faulting on a steeply dipping fracture system within the caldera. Repeated trapdoor faulting over geological time has formed an arcuate intra-caldera ridge within Sierra Negra and may have acted to relax stresses above the magma chamber, inhibiting summit eruptions. Similar processes may help explain large uplift unaccompanied by eruptive activity at other volcanoes.

    @Article{amelungJonssonZebkerSegallNature2000DInSARGalapagosVolcanoes,
    author = {Amelung, Falk and Jonsson, Sigurjon and Zebker, Howard and Segall, Paul},
    title = {Widespread uplift and trapdoor faulting on Galapagos volcanoes observed with radar interferometry},
    journal = {Nature},
    year = {2000},
    volume = {407},
    number = {6807},
    pages = {993--996},
    month = oct,
    issn = {0028-0836},
    abstract = {Volcanic uplift, caused by the accumulation of magma in subsurface reservoirs, is a common precursor to eruptions. But, for some volcanoes, uplift of metres or more has not yet led to an eruption. Here we present displacement maps of volcanoes in the Galapagos Islands, constructed using satellite radar interferometry, that might help explain this dichotomy. We show that all but one of the seven volcanoes on the islands of Isabela and Fernandina deformed during 1992-99. Cerro Azul and Fernandina erupted during the observation period and show evidence of inflation, co-eruptive deflation and shallow dyke intrusion. In contrast, the largest volcano, Sierra Negra, has not erupted, yet exhibits spatially and temporally variable deformation, with a maximum uplift of 2.7 m between 1992 and 1999, which can be modelled by a shallow inflating sill. Inflation during 1997-98, however, was accompanied by 'trapdoor' faulting on a steeply dipping fracture system within the caldera. Repeated trapdoor faulting over geological time has formed an arcuate intra-caldera ridge within Sierra Negra and may have acted to relax stresses above the magma chamber, inhibiting summit eruptions. Similar processes may help explain large uplift unaccompanied by eruptive activity at other volcanoes.},
    comment = {10.1038/35039604},
    file = {:amelungJonssonZebkerSegallNature2000DInSARGalapagosVolcanoes.pdf:PDF},
    keywords = {SAR Processing, Interferometry, SAR interferometry, differential SAR interferometry, DInSAR, Deformation Mapping, Deformation Monitoring, ERS-1, ERS-2, Displacement, Surface Displacement, Surface Deformation, Spaceborne SAR, C-band, Volcano, Galapagos, deflation, Galapagos Islands, Cerro Azul, Fernandina, co-eruptive deflation, deflation, dyke intrusion},
    owner = {ofrey},
    pdf = {../../../docs/amelungJonssonZebkerSegallNature2000DInSARGalapagosVolcanoes.pdf},
    url = {http://dx.doi.org/10.1038/35039604},
    
    }
    


  2. Marc Bara, Rolf Scheiber, Antoni Broquetas, and Alberto Moreira. Interferometric SAR signal analysis in the presence of squint. IEEE Transactions on Geoscience and Remote Sensing, 38(5):2164-2178, September 2000. Keyword(s): SAR Processing, InSAR, Interferometry, SAR Interferometry, Airborne SAR, Phase Ramp, Impulse Response Function, IRF Analysis, Phase Plots, E-SAR, geophysical techniques, radar imaging, remote sensing by radar, synthetic aperture radar, terrain mapping, topography (Earth), geophysical measurement technique, high squint angle, impulse response function, interferometric SAR, land surface, misregistration, phase bias, phase ramp, radar imaging, radar remote sensing, squint, synthetic aperture radar, terrain mapping, topography.
    Abstract: This paper develops an analysis of the SAR impulse response function from the interferometric point of view, with the intention of studying its phase behavior in the presence of high squint angle values. It will be pointed out that in this case, a phase ramp is present in the range direction, which, in combination with a certain degree of misregistration between the two images induces an offset in the generated interferometric phase. This behavior, if not compensated, imposes strong limits on the performance of the interferometric techniques in a squinted case, especially for airborne SAR systems. The article proposes two new techniques, which are appropriate to correct the phase bias coming from this source. The first one is based on a modification of the azimuth compression filter, which cancels the phase ramp of the range impulse response function for one specific squint value. In case the SAR processing is performed with variable squint over range, the authors propose a second method oriented to estimating the expected misregistration and thus, the phase bias by means of an iterative approach. Simulated data as well as real corner reflector responses are used to show that the correct topography can be recovered precisely even in the presence of phase bias coming from the squinted geometry.

    @Article{baraScheiberBroquetasMoreira2000:InSARSquinted,
    Title = {{Interferometric SAR signal analysis in the presence of squint}},
    Author = {Bara, Marc and Scheiber, Rolf and Broquetas, Antoni and Moreira, Alberto},
    Doi = {10.1109/36.868875},
    ISSN = {0196-2892},
    Month = {Sep},
    Number = {5},
    Pages = {2164-2178},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=868875&isnumber=18811},
    Volume = {38},
    Year = {2000},
    Abstract = {This paper develops an analysis of the SAR impulse response function from the interferometric point of view, with the intention of studying its phase behavior in the presence of high squint angle values. It will be pointed out that in this case, a phase ramp is present in the range direction, which, in combination with a certain degree of misregistration between the two images induces an offset in the generated interferometric phase. This behavior, if not compensated, imposes strong limits on the performance of the interferometric techniques in a squinted case, especially for airborne SAR systems. The article proposes two new techniques, which are appropriate to correct the phase bias coming from this source. The first one is based on a modification of the azimuth compression filter, which cancels the phase ramp of the range impulse response function for one specific squint value. In case the SAR processing is performed with variable squint over range, the authors propose a second method oriented to estimating the expected misregistration and thus, the phase bias by means of an iterative approach. Simulated data as well as real corner reflector responses are used to show that the correct topography can be recovered precisely even in the presence of phase bias coming from the squinted geometry.},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, InSAR, Interferometry, SAR Interferometry, Airborne SAR , Phase Ramp, Impulse Response Function, IRF Analysis, Phase Plots, E-SAR, geophysical techniques, radar imaging, remote sensing by radar, synthetic aperture radar, terrain mapping, topography (Earth), geophysical measurement technique, high squint angle, impulse response function, interferometric SAR, land surface, misregistration, phase bias, phase ramp, radar imaging, radar remote sensing, squint, synthetic aperture radar, terrain mapping, topography},
    Owner = {ofrey},
    Pdf = {../../../docs/baraScheiberBroquetasMoreira2000.pdf} 
    }
    


  3. Roland Bürgmann, Paul A. Rosen, and Eric J. Fielding. Synthetic Aperture Radar Interferometry to Measure Earth's Surface Topography and Its Deformation. Annual Review of Earth and Planetary Sciences, 28(1):169-209, 2000. Keyword(s): SAR Processing, Decorrelation, Temporal Decorrelation, Differential Interferometry, DInSAR, SAR Interferometry, Coherence, Synthetic aperture radar, SAR interferometry, differential SAR interferometry, DInSAR, interferometric stacking, deformation monitoring, subsidence monitoring, deformation measurements,.
    Abstract: Synthetic aperture radar interferometry (InSAR) from Earth-orbiting spacecraft provides a new tool to map global topography and deformation of the Earth's surface. Radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter-scale accuracy. These data sets aid in the analysis and interpretation of tectonic and volcanic landscapes. If the Earth's surface deformed between two radar image acquisitions, a map of the surface displacement with tens-of-meters resolution and subcentimeter accuracy can be constructed. This review gives a basic overview of InSAR for Earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of InSAR for mapping the topography and deformation of the Earth.

    @Article{buergmannRosenFielding2000InSARReviewPaperApplicationOriented,
    author = {Roland B{\"u}rgmann and Paul A. Rosen and Eric J. Fielding},
    title = {Synthetic Aperture Radar Interferometry to Measure Earth's Surface Topography and Its Deformation},
    journal = {Annual Review of Earth and Planetary Sciences},
    year = {2000},
    volume = {28},
    number = {1},
    pages = {169-209},
    abstract = {Synthetic aperture radar interferometry (InSAR) from Earth-orbiting spacecraft provides a new tool to map global topography and deformation of the Earth's surface. Radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter-scale accuracy. These data sets aid in the analysis and interpretation of tectonic and volcanic landscapes. If the Earth's surface deformed between two radar image acquisitions, a map of the surface displacement with tens-of-meters resolution and subcentimeter accuracy can be constructed. This review gives a basic overview of InSAR for Earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of InSAR for mapping the topography and deformation of the Earth.},
    doi = {10.1146/annurev.earth.28.1.169},
    eprint = {http://dx.doi.org/10.1146/annurev.earth.28.1.169},
    file = {:buergmannRosenFielding2000InSARReviewPaperApplicationOriented.pdf:PDF},
    keywords = {SAR Processing, Decorrelation, Temporal Decorrelation, Differential Interferometry, DInSAR, SAR Interferometry, Coherence, Synthetic aperture radar, SAR interferometry, differential SAR interferometry, DInSAR, interferometric stacking, deformation monitoring, subsidence monitoring, deformation measurements,},
    pdf = {../../../docs/buergmannRosenFielding2000InSARReviewPaperApplicationOriented.pdf},
    url = {http://dx.doi.org/10.1146/annurev.earth.28.1.169},
    
    }
    


  4. Curtis W. Chen and Howard A. Zebker. Network approaches to two-dimensional phase unwrapping: intractability and two new algorithms. J. Opt. Soc. Am. A, 17(3):401-414, March 2000. Keyword(s): SAR Processing, phase unwrapping, SNAPHU, Interferometry, InSAR, SAR Interferometry, Synthetic aperture radar, Phase.
    Abstract: Two-dimensional (2-D) phase unwrapping, that is, deducing unambiguous phase values from a 2-D array of values known only modulo 2$\pi$, is a key step in interpreting data acquired with synthetic aperture radar interferometry. Noting the recent network formulation of the phase unwrapping problem, we apply here some well-established ideas of network theory to formalize the problem, analyze its complexity, and derive algorithms for its solution. It has been suggested that the objective of phase unwrapping should be to minimize the total number of places where unwrapped and wrapped phase gradients differ. Here we use network constructions to show that this so-called minimum L0-norm problem is NP-hard, or one that complexity theory suggests is impossible for efficient algorithms to solve exactly. Therefore we must instead find approximate solutions; we present two new algorithms for doing so. The first uses the network ideas of shortest paths and spanning trees to improve on the Goldstein et al. residue-cut algorithm \[Radio Sci.23, 713 (1988)\]. Our improved algorithm is very fast, provides complete coverage, and allows user-defined weights. With our second algorithm, we extend the ideas of linear network flow problems to the nonlinear L0 case. This algorithm yields excellent approximations to the minimum L0 norm. Using interferometric data, we demonstrate that our algorithms are highly competitive with other existing algorithms in speed and accuracy, outperforming them in the cases presented here.

    @Article{chenZebkerJOptSoc2000SNAPHUNetworkApproachesTo2DPhaseUnwrapping,
    author = {Curtis W. Chen and Howard A. Zebker},
    title = {Network approaches to two-dimensional phase unwrapping: intractability and two new algorithms},
    journal = {J. Opt. Soc. Am. A},
    year = {2000},
    volume = {17},
    number = {3},
    pages = {401-414},
    month = mar,
    abstract = {Two-dimensional (2-D) phase unwrapping, that is, deducing unambiguous phase values from a 2-D array of values known only modulo 2$\pi$, is a key step in interpreting data acquired with synthetic aperture radar interferometry. Noting the recent network formulation of the phase unwrapping problem, we apply here some well-established ideas of network theory to formalize the problem, analyze its complexity, and derive algorithms for its solution. It has been suggested that the objective of phase unwrapping should be to minimize the total number of places where unwrapped and wrapped phase gradients differ. Here we use network constructions to show that this so-called minimum L0-norm problem is NP-hard, or one that complexity theory suggests is impossible for efficient algorithms to solve exactly. Therefore we must instead find approximate solutions; we present two new algorithms for doing so. The first uses the network ideas of shortest paths and spanning trees to improve on the Goldstein et al. residue-cut algorithm \[Radio Sci.23, 713 (1988)\]. Our improved algorithm is very fast, provides complete coverage, and allows user-defined weights. With our second algorithm, we extend the ideas of linear network flow problems to the nonlinear L0 case. This algorithm yields excellent approximations to the minimum L0 norm. Using interferometric data, we demonstrate that our algorithms are highly competitive with other existing algorithms in speed and accuracy, outperforming them in the cases presented here.},
    doi = {10.1364/JOSAA.17.000401},
    file = {:chenZebkerJOptSoc2000SNAPHUNetworkApproachesTo2DPhaseUnwrapping.pdf:PDF},
    keywords = {SAR Processing, phase unwrapping, SNAPHU,Interferometry; InSAR, SAR Interferometry, Synthetic aperture radar; Phase},
    owner = {ofrey},
    publisher = {OSA},
    url = {http://josaa.osa.org/abstract.cfm?URI=josaa-17-3-401},
    
    }
    


  5. Marina Dragosevic and Burkhard Plache. Doppler Tracker for a Spaceborne ScanSAR System. IEEE Transactions on Aerospace and Electronic Systems, 36(3):907-924, 2000. Keyword(s): SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, Doppler Tracker, Attitude Angles, Doppler Ambiguity Resolver, DAR, Satellite SAR.
    Abstract: This paper presents a methodology for tracking the Doppler parameters in long swaths of ScanSAR signals. The approach is entirely developed around the physical model of the Doppler effect, parameterized in terms of the spacecraft attitude angles. A new, combined algorithm is designed to estimate yaw and pitch and resolve the PRF (pulse repetition frequency) ambiguity using all available, current, and past, return samples. It is shown that the variance of the Doppler centroid (DC) estimates can be brought down to the low single-digit Hz level with computationally simple estimation algorithms

    @Article{dragosevic00:DopCentrEst,
    Title = {{Doppler Tracker for a Spaceborne ScanSAR System}},
    Author = {Marina Dragosevic and Burkhard Plache},
    Number = {3},
    Pages = {907-924},
    Url = {http://ieeexplore.ieee.org/iel5/7/18840/00869510.pdf},
    Volume = {36},
    Year = {2000},
    Abstract = {This paper presents a methodology for tracking the Doppler parameters in long swaths of ScanSAR signals. The approach is entirely developed around the physical model of the Doppler effect, parameterized in terms of the spacecraft attitude angles. A new, combined algorithm is designed to estimate yaw and pitch and resolve the PRF (pulse repetition frequency) ambiguity using all available, current, and past, return samples. It is shown that the variance of the Doppler centroid (DC) estimates can be brought down to the low single-digit Hz level with computationally simple estimation algorithms},
    Journal = {IEEE Transactions on Aerospace and Electronic Systems},
    Keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, Doppler Tracker, Attitude Angles, Doppler Ambiguity Resolver, DAR, Satellite SAR},
    Pdf = {../../../docs/dragosevic00.pdf} 
    }
    


  6. A. Ferretti, C. Prati, and F. Rocca. Nonlinear subsidence rate estimation using permanent scatterers in differential SAR interferometry. IEEE Trans. Geosci. Remote Sens., 38(5):2202 -2212, September 2000. Keyword(s): SAR Processing, Persistent, Scatterer Interferometry, PSI, deformation measurement, displacement measurement, InSAR, absidence, atmospheric phase contribution, differential SAR interferometry, downlift, geodesy, geophysical measurement technique, nonlinear motion, nonlinear subsidence rate estimation, permanent scatterer, phase unwrapping, radar remote sensing, subsidence, synthetic aperture radar, tectonics, terrain mapping, uplift, urban area, geodesy, geophysical techniques, remote sensing by radar, synthetic aperture radar, tectonics, terrain mapping;.
    Abstract: Discrete and temporarily stable natural reflectors or permanent scatterers (PS) can be identified from long temporal series of interferometric SAR images even with baselines larger than the so-called critical baseline. This subset of image pixels can be exploited successfully for high accuracy differential measurements. The authors discuss the use of PS in urban areas, like Pomona, CA, showing subsidence and absidence effects. A new approach to the estimation of the atmospheric phase contributions, and the local displacement field is proposed based on simple statistical assumptions. New solutions are presented in order to cope with nonlinear motion of the targets

    @Article{ferrettiPratiRocca2000PSINonLinear,
    author = {Ferretti, A. and Prati, C. and Rocca, F.},
    title = {Nonlinear subsidence rate estimation using permanent scatterers in differential SAR interferometry},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {2000},
    volume = {38},
    number = {5},
    pages = {2202 -2212},
    month = {sep},
    issn = {0196-2892},
    abstract = {Discrete and temporarily stable natural reflectors or permanent scatterers (PS) can be identified from long temporal series of interferometric SAR images even with baselines larger than the so-called critical baseline. This subset of image pixels can be exploited successfully for high accuracy differential measurements. The authors discuss the use of PS in urban areas, like Pomona, CA, showing subsidence and absidence effects. A new approach to the estimation of the atmospheric phase contributions, and the local displacement field is proposed based on simple statistical assumptions. New solutions are presented in order to cope with nonlinear motion of the targets},
    doi = {10.1109/36.868878},
    file = {:ferrettiPratiRocca2000PSINonLinear.pdf:PDF},
    keywords = {SAR Processing, Persistent, Scatterer Interferometry, PSI, deformation measurement, displacement measurement, InSAR;absidence;atmospheric phase contribution;differential SAR interferometry;downlift;geodesy;geophysical measurement technique;nonlinear motion;nonlinear subsidence rate estimation;permanent scatterer;phase unwrapping;radar remote sensing;subsidence;synthetic aperture radar;tectonics;terrain mapping;uplift;urban area;geodesy;geophysical techniques;remote sensing by radar;synthetic aperture radar;tectonics;terrain mapping;},
    
    }
    


  7. A. Laurence Gray, Karim E. Mattar, and George Sofko. Influence of ionospheric electron density fluctuations on satellite radar interferometry. Geophysical Research Letters, 27(10):1451-1454, 2000. Keyword(s): SAR Processing, ionospheric techniques, radar interferometry, synthetic aperture radar, azimuth shift, interferometric SAR ionosphere correction, ionospheric geometric distortion, Interferometry, Ionosphere, L-band, Synthetic aperture radar.
    Abstract: Evidence is presented that auroral zone ionospheric disturbances can influence satellite radar interferometry (SRI) obtained with the RADARSAT, ERS and JERS-1 satellites. Fluctuations in ionospheric electron density can lead to an azimuth shift modulation in synthetic aperture radar (SAR) imagery, which can be detected using SRI. Measurements of azimuth shift in SRI can help to differentiate ionospheric from tropospheric propagation problems, and to understand better the impact of the ionosphere on spaceborne SAR. Further, SRI azimuth shift modulation may be useful in mapping patterns of polar auroral zone ionospheric disturbances over large distances.

    @Article{grayMattarSofkoGRL2000IonosphericTEConInSAR,
    author = {Gray, A. Laurence and Mattar, Karim E. and Sofko, George},
    title = {Influence of ionospheric electron density fluctuations on satellite radar interferometry},
    journal = {Geophysical Research Letters},
    year = {2000},
    volume = {27},
    number = {10},
    pages = {1451-1454},
    abstract = {Evidence is presented that auroral zone ionospheric disturbances can influence satellite radar interferometry (SRI) obtained with the RADARSAT, ERS and JERS-1 satellites. Fluctuations in ionospheric electron density can lead to an azimuth shift modulation in synthetic aperture radar (SAR) imagery, which can be detected using SRI. Measurements of azimuth shift in SRI can help to differentiate ionospheric from tropospheric propagation problems, and to understand better the impact of the ionosphere on spaceborne SAR. Further, SRI azimuth shift modulation may be useful in mapping patterns of polar auroral zone ionospheric disturbances over large distances.},
    doi = {10.1029/2000GL000016},
    eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2000GL000016},
    file = {:grayMattarSofkoGRL2000IonosphericTEConInSAR.pdf:PDF},
    keywords = {SAR Processing, ionospheric techniques, radar interferometry, synthetic aperture radar,azimuth shift, interferometric SAR ionosphere correction, ionospheric geometric distortion, Interferometry, Ionosphere, L-band, Synthetic aperture radar},
    url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2000GL000016},
    
    }
    


  8. Jong-Sen Lee, D.L. Schuler, and T.L. Ainsworth. Polarimetric SAR data compensation for terrain azimuth slope. IEEE Transactions on Geoscience and Remote Sensing, 38(5):2153-2163, 2000. Keyword(s): geophysical techniques, radar imaging, radar polarimetry, remote sensing by radar, synthetic aperture radar, terrain mapping, POLSAR, azimuth slope variation, data compensation, effective scattering pixel area, geophysical measurement technique, land surface, polarimetric SAR, polarization, radar cross section, radar imaging, radar polarimetry, radar remote sensing, radiometric slope correction, synthetic aperture radar, terrain mapping.
    Abstract: This paper addresses the problem of polarimetric SAR (POLSAR) data

    @Article{LeeSchulerAinsworth00:PolSARTerrainSlope,
    Title = {{Polarimetric SAR data compensation for terrain azimuth slope}},
    Author = {Lee, Jong-Sen and Schuler, D.L. and Ainsworth, T.L.},
    Number = {5},
    Pages = {2153--2163},
    Volume = {38},
    Year = {2000},
    Abstract = {This paper addresses the problem of polarimetric SAR (POLSAR) data},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {geophysical techniques, radar imaging, radar polarimetry, remote sensing by radar, synthetic aperture radar, terrain mapping, POLSAR, azimuth slope variation, data compensation, effective scattering pixel area, geophysical measurement technique, land surface, polarimetric SAR, polarization, radar cross section, radar imaging, radar polarimetry, radar remote sensing, radiometric slope correction, synthetic aperture radar, terrain mapping},
    Owner = {ofrey},
    Pdf = {../../../docs/LeeSchulerAinsworth00.pdf} 
    }
    


  9. Juan M. Lopez-Sanchez and Joaquim Fortuny-Guasch. 3-D Radar Imaging Using Range Migration Techniques. IEEE Transactions on Antennas and Propagation, 48(5):728-737, May 2000. Keyword(s): SAR Processing, Near Field, SAR Tomography, Tomography, Radar Imaging, Range Migration Algorithm, Wavenumber Domain Algorithm, omega-k, 3D imaging algorithm, Stationary Phase Method.
    Abstract: An imaging system with three-dimensional (3-D) capability can be implemented by using a stepped frequency radar which synthesizes a two-dimensional (2-D) planar aperture. A 3-D image can be formed by coherently integrating the backscatter data over the measured frequency band and the two spatial coordinates of the 2-D synthetic aperture. This paper presents a near-field 3-D synthetic aperture radar (SAR) imaging algorithm. This algorithm is an extension of the 2-D range migration algorithm (RMA). The presented formulation is justified by using the method of the stationary phase (MSP). Implementation aspects including the sampling criteria, resolutions, and computational complexity are assessed. The high computational efficiency and accurate image reconstruction of the algorithm are demonstrated both with numerical simulations and measurements using an outdoor linear SAR system.

    @Article{lopez00:statphase,
    Title = {{3-D Radar Imaging Using Range Migration Techniques}},
    Author = {Juan M. Lopez-Sanchez and Joaquim Fortuny-Guasch},
    Month = May,
    Number = {5},
    Pages = {728-737},
    Url = {http://ieeexplore.ieee.org/iel5/8/18576/00855491.pdf},
    Volume = {48},
    Year = {2000},
    Abstract = {An imaging system with three-dimensional (3-D) capability can be implemented by using a stepped frequency radar which synthesizes a two-dimensional (2-D) planar aperture. A 3-D image can be formed by coherently integrating the backscatter data over the measured frequency band and the two spatial coordinates of the 2-D synthetic aperture. This paper presents a near-field 3-D synthetic aperture radar (SAR) imaging algorithm. This algorithm is an extension of the 2-D range migration algorithm (RMA). The presented formulation is justified by using the method of the stationary phase (MSP). Implementation aspects including the sampling criteria, resolutions, and computational complexity are assessed. The high computational efficiency and accurate image reconstruction of the algorithm are demonstrated both with numerical simulations and measurements using an outdoor linear SAR system.},
    Journal = {IEEE Transactions on Antennas and Propagation},
    Keywords = {SAR Processing, Near Field, SAR Tomography, Tomography, Radar Imaging, Range Migration Algorithm, Wavenumber Domain Algorithm, omega-k, 3D imaging algorithm, Stationary Phase Method},
    Pdf = {../../../docs/lopez00.pdf} 
    }
    


  10. Christian Matzler and A Standley. Technical note: Relief effects for passive microwave remote sensing. 2000.
    @Article{Maetzler2000,
    author = {Matzler, Christian and Standley, A},
    title = {Technical note: Relief effects for passive microwave remote sensing},
    year = {2000},
    owner = {ofrey},
    publisher = {Taylor \& Francis},
    
    }
    


  11. Richard Rau and James H. McClellan. Analytic Models and Postprocessing Techniques for UWB SAR. IEEE Transactions on Aerospace and Electronic Systems, 36(4):1058-1074, October 2000. Keyword(s): SAR Processing, Back-Projection, Ultra-Wideband SAR, TDBP, Time-Domain Back-Projection.
    Abstract: The latest generation of fully polarimetric, ultra wideband (UWB), wide angle, low frequency, foliage and ground-penetrating synthetic aperture radars (SARs) record huge amounts of data that must be processed to focus high quality images. At the same time only a few small subimages contain important information. We investigate the relationship between the focused image and the reflectivity profile and show that a linear shift-invariant model adequately represents the overall process when the focusing is done with a backprojection algorithm over a constant integration angle. The derived signal model can be used to replace many computationally expensive processing techniques, previously performed on the raw data, with equivalent postprocessing algorithms which can be applied selectively to subimages.

    @Article{RauMcClellan00:UWB,
    Title = {{Analytic Models and Postprocessing Techniques for UWB SAR}},
    Author = {Richard Rau and James H. McClellan},
    Month = Oct,
    Number = {4},
    Pages = {1058-1074},
    Volume = {36},
    Year = {2000},
    Abstract = {The latest generation of fully polarimetric, ultra wideband (UWB), wide angle, low frequency, foliage and ground-penetrating synthetic aperture radars (SARs) record huge amounts of data that must be processed to focus high quality images. At the same time only a few small subimages contain important information. We investigate the relationship between the focused image and the reflectivity profile and show that a linear shift-invariant model adequately represents the overall process when the focusing is done with a backprojection algorithm over a constant integration angle. The derived signal model can be used to replace many computationally expensive processing techniques, previously performed on the raw data, with equivalent postprocessing algorithms which can be applied selectively to subimages.},
    Journal = {IEEE Transactions on Aerospace and Electronic Systems},
    Keywords = {SAR Processing, Back-Projection, Ultra-Wideband SAR, TDBP, Time-Domain Back-Projection},
    Pdf = {../../../docs/rauMcClellan00.pdf} 
    }
    


  12. A. Reigber and A. Moreira. First Demonstration of Airborne SAR Tomography Using Multibaseline L-Band Data. IEEE Transactions on Geoscience and Remote Sensing, 38(5):2142-2152, 2000. Keyword(s): SAR Processing, airborne radar, geophysical techniques, radar imaging, radar polarimetry, remote sensing by radar, synthetic aperture radar, terrain mapping, topography (Earth), InSAR, L-Band, SAR interferometry, SAR Tomography, Tomography, UHF, airborne radar, aperture synthesis, geophysical measurement technique, height ambiguity, land surface, multibaseline imaging geometry, multibaseline method, phase difference, radar imaging, radar polarimetry, radar remote sensing, synthetic aperture radar, terrain mapping, tomographic imaging, topography, undersampled spatial distribution, ESAR.
    Abstract: In synthetic aperture radar (SAR) interferometry, the phase differences between two different sensor positions are used to estimate the terrain topography. Although it is possible in this way to find a three-dimensional (3D) surface representation, the distribution of the different scatterers in the height direction at a fixed range and azimuth position remains unknown. Contrary to this, tomographic techniques enable a real geometric resolution capability in the height direction and introduce new possibilities for many applications and inversion problems. Even misinterpretations in SAR images caused by layover and foreshortening effects can be solved by the tomographic processing. In this paper, the successful experimental realization of polarimetric airborne SAR tomography is demonstrated for the first time. The authors present the concept of aperture synthesis for tomographic imaging for the case of a multibaseline imaging geometry and discuss the constraints arising from the limited number of flight tracks. They propose a method for reduction of the height ambiguities associated to the irregular and undersampled spatial distribution of the imaging positions. Finally, they address the experimental requirements for polarimetric airborne SAR tomography and show experimental results using a multibaseline data set acquired in L-band by DLR's experimental SAR (E-SAR) of a test-site near Oberpfaffenhofen, Germany.

    @Article{reigberMoreira00:TomoLBand,
    Title = {{First Demonstration of Airborne SAR Tomography Using Multibaseline L-Band Data}},
    Author = {Reigber, A. and Moreira, A.},
    Number = {5},
    Pages = {2142--2152},
    Url = {http://ieeexplore.ieee.org/iel5/36/18811/00868873.pdf},
    Volume = {38},
    Year = {2000},
    Abstract = {In synthetic aperture radar (SAR) interferometry, the phase differences between two different sensor positions are used to estimate the terrain topography. Although it is possible in this way to find a three-dimensional (3D) surface representation, the distribution of the different scatterers in the height direction at a fixed range and azimuth position remains unknown. Contrary to this, tomographic techniques enable a real geometric resolution capability in the height direction and introduce new possibilities for many applications and inversion problems. Even misinterpretations in SAR images caused by layover and foreshortening effects can be solved by the tomographic processing. In this paper, the successful experimental realization of polarimetric airborne SAR tomography is demonstrated for the first time. The authors present the concept of aperture synthesis for tomographic imaging for the case of a multibaseline imaging geometry and discuss the constraints arising from the limited number of flight tracks. They propose a method for reduction of the height ambiguities associated to the irregular and undersampled spatial distribution of the imaging positions. Finally, they address the experimental requirements for polarimetric airborne SAR tomography and show experimental results using a multibaseline data set acquired in L-band by DLR's experimental SAR (E-SAR) of a test-site near Oberpfaffenhofen, Germany.},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, airborne radar, geophysical techniques, radar imaging, radar polarimetry, remote sensing by radar, synthetic aperture radar, terrain mapping, topography (Earth), InSAR, L-Band, SAR interferometry, SAR Tomography, Tomography, UHF, airborne radar, aperture synthesis, geophysical measurement technique, height ambiguity, land surface, multibaseline imaging geometry, multibaseline method, phase difference, radar imaging, radar polarimetry, radar remote sensing, synthetic aperture radar, terrain mapping, tomographic imaging, topography, undersampled spatial distribution, ESAR},
    Owner = {ofrey},
    Pdf = {../../../docs/reigberMoreira00.pdf} 
    }
    


  13. Paul A. Rosen, Scott Hensley, Ian R. Joughin, Fuk K. Li, Soren N. Madsen, Ernesto Rodriguez, and Richard M. Goldstein. Synthetic aperture radar interferometry. Proceedings of the IEEE, 88(3):333-382, March 2000. Keyword(s): Review Paper, SAR Processing, SAR Interferometry, differential SAR Interferometry, DInSAR, InSAR, deformation mapping, surface deformation, surface displacement, cartography, geodesy, geophysical techniques, radiowave interferometry, remote sensing by laser beam, surface topography measurement, synthetic aperture radar, cartography, coherent radar signal phase, geodesy, land cover characterization, natural hazards, radar remote sensing, surface topography, synthetic aperture radar interferometry, Extraterrestrial measurements, Geophysical measurements, Hazards, Radar antennas, Radar imaging, Remote sensing, Spaceborne radar, Surface topography, Synthetic aperture radar interferometry, Vegetation mapping.
    Abstract: Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristic of the surface. By exploiting the phase of the coherent radar signal, interferometry has transformed radar remote sensing from a largely interpretive science to a quantitative tool, with applications in cartography, geodesy, land cover characterization, and natural hazards. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

    @Article{rosenHensleyJoughinFukMadsenRodriguezGoldsteinProcOfIEEE2000SyntheticApertureRadarInterferometryReviewPaper,
    author = {Rosen, Paul A. and Hensley, Scott and Joughin, Ian R. and Fuk K. Li and Madsen, S{\o}ren N. and Rodriguez, Ernesto and Goldstein, Richard M.},
    title = {Synthetic aperture radar interferometry},
    journal = {Proceedings of the {IEEE}},
    year = {2000},
    volume = {88},
    number = {3},
    pages = {333-382},
    month = mar,
    issn = {0018-9219},
    abstract = {Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristic of the surface. By exploiting the phase of the coherent radar signal, interferometry has transformed radar remote sensing from a largely interpretive science to a quantitative tool, with applications in cartography, geodesy, land cover characterization, and natural hazards. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.},
    doi = {10.1109/5.838084},
    file = {:rosenHensleyJoughinFukMadsenRodriguezGoldsteinProcOfIEEE2000SyntheticApertureRadarInterferometryReviewPaper.pdf:PDF},
    keywords = {Review Paper, SAR Processing, SAR Interferometry, differential SAR Interferometry, DInSAR, InSAR, deformation mapping, surface deformation, surface displacement, cartography;geodesy;geophysical techniques;radiowave interferometry;remote sensing by laser beam; surface topography measurement;synthetic aperture radar;cartography;coherent radar signal phase; geodesy;land cover characterization;natural hazards;radar remote sensing;surface topography; synthetic aperture radar interferometry;Extraterrestrial measurements;Geophysical measurements; Hazards;Radar antennas;Radar imaging;Remote sensing;Spaceborne radar;Surface topography; Synthetic aperture radar interferometry;Vegetation mapping},
    pdf = {../../../docs/rosenHensleyJoughinFukMadsenRodriguezGoldsteinProcOfIEEE2000SyntheticApertureRadarInterferometryReviewPaper.pdf},
    
    }
    


  14. K. Sarabandi and Y.-C. Lin. Simulation of interferometric SAR response for characterizing the scattering phase center statistics of forest canopies. IEEE Trans. Geosci. Remote Sens., 38(1):115-125, January 2000. Keyword(s): InSAR, Monte Carlo simulation, SAR, backscatter, coherent scattering model, equivalent scatterer, forest, forest canopy, forestry, fractal, geophysical measurement technique, interferometric SAR, physical parameters, radar remote sensing, radar theory, scatterer collection, scattering phase center statistics, simulation, synthetic aperture radar, vegetation mapping, Monte Carlo methods, backscatter, forestry, fractals, geophysical techniques, radar cross-sections, radar theory, remote sensing by radar, synthetic aperture radar, vegetation mapping;.
    Abstract: A coherent scattering model for tree canopies is employed in order to characterize the sensitivity of an interferometric SAR (INSAR) response to the physical parameters of forest stands. The concept of an equivalent scatterer for a collection of scatterers within a pixel, representing the vegetation particles of tree structures, is used for identifying the scattering phase center of the pixel whose height is measured by an INSAR. Combining the recently developed coherent scattering model for tree canopies and the INSAR Delta;k-radar-equivalence algorithm, accurate statistics of the scattering phase-center location of forest stands are obtained numerically for the first time. The scattering model is based on a Monte Carlo simulation of scattering from fractal-generated tree structures, and therefore is capable of preserving the absolute phase of the backscatter. The model can also account for coherent effects due to the relative position of individual scatterers and the inhomogeneous extinction experienced by a coherent wave propagating through the random collection of vegetation particles. The location of the scattering phase center and the correlation coefficient are computed using the Delta;k-radar equivalence simply by simulating the backscatter response at two slightly different frequencies. The model is successfully validated using the measured data acquired by JPL TOPSAR over a selected pine stand in Raco, MI. A sensitivity analysis is performed to characterize the response of coniferous and deciduous forest stands to a multifrequency and multipolarization INSAR in order to determine an optimum system configuration for remote sensing of forest parameters

    @Article{823906,
    author = {Sarabandi, K. and Lin, Y.-C.},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    title = {Simulation of interferometric SAR response for characterizing the scattering phase center statistics of forest canopies},
    year = {2000},
    issn = {0196-2892},
    month = {jan},
    number = {1},
    pages = {115-125},
    volume = {38},
    abstract = {A coherent scattering model for tree canopies is employed in order to characterize the sensitivity of an interferometric SAR (INSAR) response to the physical parameters of forest stands. The concept of an equivalent scatterer for a collection of scatterers within a pixel, representing the vegetation particles of tree structures, is used for identifying the scattering phase center of the pixel whose height is measured by an INSAR. Combining the recently developed coherent scattering model for tree canopies and the INSAR Delta;k-radar-equivalence algorithm, accurate statistics of the scattering phase-center location of forest stands are obtained numerically for the first time. The scattering model is based on a Monte Carlo simulation of scattering from fractal-generated tree structures, and therefore is capable of preserving the absolute phase of the backscatter. The model can also account for coherent effects due to the relative position of individual scatterers and the inhomogeneous extinction experienced by a coherent wave propagating through the random collection of vegetation particles. The location of the scattering phase center and the correlation coefficient are computed using the Delta;k-radar equivalence simply by simulating the backscatter response at two slightly different frequencies. The model is successfully validated using the measured data acquired by JPL TOPSAR over a selected pine stand in Raco, MI. A sensitivity analysis is performed to characterize the response of coniferous and deciduous forest stands to a multifrequency and multipolarization INSAR in order to determine an optimum system configuration for remote sensing of forest parameters},
    doi = {10.1109/36.823906},
    keywords = {InSAR;Monte Carlo simulation;SAR;backscatter;coherent scattering model;equivalent scatterer;forest;forest canopy;forestry;fractal;geophysical measurement technique;interferometric SAR;physical parameters;radar remote sensing;radar theory;scatterer collection;scattering phase center statistics;simulation;synthetic aperture radar;vegetation mapping;Monte Carlo methods;backscatter;forestry;fractals;geophysical techniques;radar cross-sections;radar theory;remote sensing by radar;synthetic aperture radar;vegetation mapping;},
    
    }
    


  15. Rolf Scheiber and Alberto Moreira. Coregistration of interferometric SAR images using spectral diversity. IEEE Transactions on Geoscience and Remote Sensing, 38(5):2179-2191, September 2000. Keyword(s): SAR Processing, Spectral Diversity, Coregistration, Image Coregistration, InSAR, SAR Interferometry, Airborne SAR, Spaceborne SAR, geophysical signal processing, geophysical techniques, image registration, radar imaging, remote sensing by radar, synthetic aperture radar, terrain mappingInSAR, complex SAR signal, geophysical measurement technique, image registration, land surface, radar imaging, radar remote sensing, relative misregistration, synthetic aperture radar, terrain mapping.
    Abstract: This article presents a technique for the determination of the relative misregistration between two interferometric SAR images. The proposed technique is based on the spectral properties of the complex SAR signal. Unlike conventional coregistration methods, the proposed technique does not need any interpolation nor cross-correlation procedures and also no coherence or fringe optimization must be performed. Instead, the phase information of different spectral looks is evaluated giving misregistration information on a pixel by pixel basis. The proposed technique is at least as accurate as the conventional algorithms and its implementation is very simple. Airborne repeat-pass interferometric data and simulated ScanSAR data are used to illustrate the operation of the proposed technique

    @Article{scheiberMoreira2000:InSARCoregistrationSpectralDiversity,
    Title = {{Coregistration of interferometric SAR images using spectral diversity}},
    Author = {Scheiber, Rolf and Moreira, Alberto},
    Doi = {10.1109/36.868876},
    Month = {sep},
    Number = {5},
    Pages = {2179-2191},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=868876&isnumber=18811},
    Volume = {38},
    Year = {2000},
    Abstract = {This article presents a technique for the determination of the relative misregistration between two interferometric SAR images. The proposed technique is based on the spectral properties of the complex SAR signal. Unlike conventional coregistration methods, the proposed technique does not need any interpolation nor cross-correlation procedures and also no coherence or fringe optimization must be performed. Instead, the phase information of different spectral looks is evaluated giving misregistration information on a pixel by pixel basis. The proposed technique is at least as accurate as the conventional algorithms and its implementation is very simple. Airborne repeat-pass interferometric data and simulated ScanSAR data are used to illustrate the operation of the proposed technique},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, Spectral Diversity, Coregistration, Image Coregistration, InSAR, SAR Interferometry, Airborne SAR, Spaceborne SAR, geophysical signal processing, geophysical techniques, image registration, radar imaging, remote sensing by radar, synthetic aperture radar, terrain mappingInSAR, complex SAR signal, geophysical measurement technique, image registration, land surface, radar imaging, radar remote sensing, relative misregistration, synthetic aperture radar, terrain mapping},
    Owner = {ofrey},
    Pdf = {../../../docs/scheiberMoreira2000.pdf} 
    }
    


  16. Robert N. Treuhaft and Paul R. Siqueira. Vertical structure of vegetated land surfaces from interferometric and polarimetric radar. Radio Science, 35:141-178, 2000. Keyword(s): SAR Processing, InSAR, Interferometry, Pol-InSAR, Multi-Baseline SAR, Vegetation Parameters, Parameter Extraction, Topography, SAR Tomography.
    Abstract: This paper describes the estimation of parameters characterizing the vertical structure of vegetated land surfaces, from combined interferometric and polarimetric radar data. Physical models expressing radar observations in terms of parameters describing vegetated land surfaces are the foundation for parameter estimation techniques. Defining a general complex cross correlation enables the unified development of models for interferometry and polarimetry, including polarimetric interferometry. Three simple physical models in this paper express this complex cross correlation in terms of vegetation parameters: (1) a randomly oriented volume, (2) a randomly oriented volume with a ground return, and (3) an oriented volume. For the first two models the parameters include vegetation height, extinction coefficient, underlying topography, and another parameter depending on ground electrical properties and roughness. For the oriented volume, additional parameters depend on the refractivity, extinction coefficients, and backscattering characteristics of waves propagating along eigenpolarizations of the vegetation volume. The above models show that the interferometric cross-correlation amplitude and the polarimetric {HHHH/VVVV} ratio both change by about 1% per meter of vegetation height change, for experimental conditions typical of airborne and spaceborne interferometric radars. These vertical-structure sensitivities prompt a parameter estimation demonstration with two-baseline TOPSAR interferometric and zero-baseline polarimetric data from the Boreal Ecosystem-Atmosphere Study (BOREAS) Southern Study Area in Prince Albert National Park, Saskatchewan, Canada. The demonstrations show the feasibility of measuring vegetation height to better than 4.2 m, underlying topography to better than 6.5 m, and the ratio of ground-to-volume power to better than 10%, using interferometry and polarimetry, coupled with parameter-constraining assumptions, concerning the degree of surface roughness. This paper suggests that single-baseline and multibaseline fully polarimetric interferometry have the potential to obviate the need for such assumptions, thereby making parameter estimation more robust, accurate, and realistic.

    @Article{treuhaftSiqueira2000:InSARVegetation,
    Title = {{Vertical structure of vegetated land surfaces from interferometric and polarimetric radar}},
    Author = {{Treuhaft}, Robert N. and {Siqueira}, Paul R.},
    Pages = {141-178},
    Volume = {35},
    Year = {2000},
    Abstract = {This paper describes the estimation of parameters characterizing the vertical structure of vegetated land surfaces, from combined interferometric and polarimetric radar data. Physical models expressing radar observations in terms of parameters describing vegetated land surfaces are the foundation for parameter estimation techniques. Defining a general complex cross correlation enables the unified development of models for interferometry and polarimetry, including polarimetric interferometry. Three simple physical models in this paper express this complex cross correlation in terms of vegetation parameters: (1) a randomly oriented volume, (2) a randomly oriented volume with a ground return, and (3) an oriented volume. For the first two models the parameters include vegetation height, extinction coefficient, underlying topography, and another parameter depending on ground electrical properties and roughness. For the oriented volume, additional parameters depend on the refractivity, extinction coefficients, and backscattering characteristics of waves propagating along eigenpolarizations of the vegetation volume. The above models show that the interferometric cross-correlation amplitude and the polarimetric {HHHH/VVVV} ratio both change by about 1% per meter of vegetation height change, for experimental conditions typical of airborne and spaceborne interferometric radars. These vertical-structure sensitivities prompt a parameter estimation demonstration with two-baseline TOPSAR interferometric and zero-baseline polarimetric data from the Boreal Ecosystem-Atmosphere Study (BOREAS) Southern Study Area in Prince Albert National Park, Saskatchewan, Canada. The demonstrations show the feasibility of measuring vegetation height to better than 4.2 m, underlying topography to better than 6.5 m, and the ratio of ground-to-volume power to better than 10%, using interferometry and polarimetry, coupled with parameter-constraining assumptions, concerning the degree of surface roughness. This paper suggests that single-baseline and multibaseline fully polarimetric interferometry have the potential to obviate the need for such assumptions, thereby making parameter estimation more robust, accurate, and realistic.},
    Journal = {Radio Science},
    Keywords = {SAR Processing, InSAR, Interferometry, Pol-InSAR, Multi-Baseline SAR, Vegetation Parameters, Parameter Extraction, Topography, SAR Tomography},
    Owner = {ofrey},
    Pdf = {../../../docs/treuhaftSiqueira2000.pdf} 
    }
    


  17. C. Wimmer, R. Siegmund, M. Schwabisch, and João Moreira. Generation of high precision DEMs of the Wadden Sea with airborneinterferometric SAR. IEEE Trans. Geosci. Remote Sens., 38(5):2234-2245, 2000. Keyword(s): SAR Processing, InSAR, Interferometry, airborne radar, bathymetry, geodesy, geophysical techniques, oceanographic regions, remote sensing by radar, seafloor phenomena, synthetic aperture radar, terrain mapping, topography (Earth), AeS-1, Bremerhaven, DEM, German Bight, Germany, InSAR, North Sea, Wadden Sea, airborne interferometric radar, airborne radar, coast, digital elevation model, geophysical measurement technique, interferometric SAR, intertidal zone, land surface topography, ocean, radar remote sensing, seafloor, synthetic aperture radar, terrain mapping, verification, Airborne SAR, Doppler Centroid Estimation.
    Abstract: This paper describes how high-precision digital elevation models(DEMs) are obtained over the Wadden Sea using the AeS-1 airborneinterferometric radar. The Wadden Sea is an intertidal zone along thecoast having height variations less than 5 m over 30 km and is free ofvegetation. The resulting DEM has a grid spacing of 2.5 m and anabsolute height accuracy of 5 cm root mean square (rms), as verified bytheodolite measurements. This paper describes the radar system, theprocessing techniques, the test area, the results, and the verificationprocedure

    @Article{wimmerSiegmundSchwaebischMoreira2000:DEMGen,
    Title = {Generation of high precision DEMs of the Wadden Sea with airborneinterferometric SAR},
    Author = {Wimmer, C. and Siegmund, R. and Schwabisch, M. and Moreira, Jo{\~a}o},
    ISSN = {0196-2892},
    Number = {5},
    Pages = {2234--2245},
    Url = {http://ieeexplore.ieee.org/iel5/36/18811/00868881.pdf},
    Volume = {38},
    Year = {2000},
    Abstract = {This paper describes how high-precision digital elevation models(DEMs) are obtained over the Wadden Sea using the AeS-1 airborneinterferometric radar. The Wadden Sea is an intertidal zone along thecoast having height variations less than 5 m over 30 km and is free ofvegetation. The resulting DEM has a grid spacing of 2.5 m and anabsolute height accuracy of 5 cm root mean square (rms), as verified bytheodolite measurements. This paper describes the radar system, theprocessing techniques, the test area, the results, and the verificationprocedure},
    Journal = {IEEE Trans. Geosci. Remote Sens.},
    Keywords = {SAR Processing, InSAR, Interferometry, airborne radar, bathymetry, geodesy, geophysical techniques, oceanographic regions, remote sensing by radar, seafloor phenomena, synthetic aperture radar, terrain mapping, topography (Earth), AeS-1, Bremerhaven, DEM, German Bight, Germany, InSAR, North Sea, Wadden Sea, airborne interferometric radar, airborne radar, coast, digital elevation model, geophysical measurement technique, interferometric SAR, intertidal zone, land surface topography, ocean, radar remote sensing, seafloor, synthetic aperture radar, terrain mapping, verification, Airborne SAR, Doppler Centroid Estimation},
    Owner = {ofrey},
    Pdf = {../../../docs/wimmerSiegmundSchwaebischMoreira2000.pdf} 
    }
    


Conference articles

  1. M. Bara, A. Broquetas, and J. Closa. Precise geometry simulation of interferometric SAR signal for air and spaceborne sensors. In Geoscience and Remote Sensing Symposium, 2000. Proceedings. IGARSS 2000. IEEE 2000 International, volume 2, pages 746-748, July 2000.
    @InProceedings{Bara2000,
    Title = {Precise geometry simulation of interferometric SAR signal for air and spaceborne sensors},
    Author = {Bara, M. and Broquetas, A. and Closa, J.},
    Booktitle = {Geoscience and Remote Sensing Symposium, 2000. Proceedings. IGARSS 2000. IEEE 2000 International},
    Doi = {10.1109/IGARSS.2000.861690},
    Month = jul,
    Pages = {746--748},
    Volume = {2},
    Year = {2000},
    Owner = {ofrey},
    Timestamp = {2009.03.05} 
    }
    


  2. T. Ekman, A. Jakobsson, and Petre Stoica. On the efficient implementation of the Capon spectral estimator. In 2000 10th European Signal Processing Conference, pages 1-4, Sep. 2000. Keyword(s): Capon, Spectral estimation, beamforming, Capon, Beamforming, Amplitude and phase preserving Capon, Covariance matrices, Frequency estimation, Estimation, Signal resolution, Signal to noise ratio, Vectors, Spectral analysis.
    Abstract: We present an efficient implementation of the Amplitude Spectrum Capon (ASC) estimator. The implementation is based on the FFT and an efficient computation of the Cholesky-factor for the inverse covariance matrix. The Cholesky-factor is obtained from the linear prediction coefficients as computed by the modified covariance method. The implementation is significantly simpler than previous implementations, and it will yield spectral estimates of a similar quality as these. A short discussion on the differences between different Capon estimators is also included.

    @InProceedings{ekmanJakobssonStoica2000EfficientImplementationOfCaponSpectralEstimator,
    author = {T. {Ekman} and A. {Jakobsson} and Petre Stoica},
    title = {On the efficient implementation of the {Capon} spectral estimator},
    booktitle = {2000 10th European Signal Processing Conference},
    year = {2000},
    pages = {1-4},
    month = {Sep.},
    abstract = {We present an efficient implementation of the Amplitude Spectrum Capon (ASC) estimator. The implementation is based on the FFT and an efficient computation of the Cholesky-factor for the inverse covariance matrix. The Cholesky-factor is obtained from the linear prediction coefficients as computed by the modified covariance method. The implementation is significantly simpler than previous implementations, and it will yield spectral estimates of a similar quality as these. A short discussion on the differences between different Capon estimators is also included.},
    file = {:ekmanJakobssonStoica2000EfficientImplementationOfCaponSpectralEstimator.pdf:PDF},
    issn = {null},
    keywords = {Capon, Spectral estimation, beamforming, Capon, Beamforming, Amplitude and phase preserving Capon, Covariance matrices;Frequency estimation;Estimation;Signal resolution;Signal to noise ratio;Vectors;Spectral analysis},
    owner = {ofrey},
    
    }
    


  3. D. G. Falconer. Radar imaging using statistical orthogonality. In E. G. Zelnio, editor, Proc. SPIE Vol. 4053, p. 10-19, Algorithms for Synthetic Aperture Radar Imagery VII, Edmund G. Zelnio; Ed., volume 4053 of Presented at the Society of Photo-Optical Instrumentation Engineers (SPIE) Conference, pages 10-19, August 2000. Keyword(s): SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR.
    @InProceedings{falconer2000:NonLinearSAR,
    Title = {{Radar imaging using statistical orthogonality}},
    Author = {Falconer, D.~G.},
    Booktitle = {Proc. SPIE Vol. 4053, p. 10-19, Algorithms for Synthetic Aperture Radar Imagery VII, Edmund G. Zelnio; Ed.},
    Editor = {{Zelnio}, E.~G.},
    Month = aug,
    Pages = {10-19},
    Series = {Presented at the Society of Photo-Optical Instrumentation Engineers (SPIE) Conference},
    Volume = {4053},
    Year = {2000},
    Adsnote = {Provided by the Smithsonian/NASA Astrophysics Data System},
    Adsurl = {http://adsabs.harvard.edu/abs/2000SPIE.4053...10F},
    Keywords = {SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR} 
    }
    


  4. Guoyongmei, Chenhao, Hongwen, and Maoshiyi. Resample in the first order motion compensation of real-time SAR processor. In 5th International Conference on Signal Processing Proceedings, 2000. WCCC-ICSP 2000, volume 3, pages 1830-1833, 2000. Keyword(s): SAR Processsing, Airborne SAR, Motion Compensation, MoComp, airborne radar, error compensation, image sampling, motion compensation, radar imaging, real-time systems, synthetic aperture radarSAR image, airborne radar, azimuth focus, first order motion compensation, image defocus, image distortion, motion error model, phase errors, real-time SAR processor, resample problem, signal amplitude, synthetic aperture radar.
    Abstract: The resample problem in the first order motion compensation of real-time SAR processor is presented. The motion error model is properly established, and the simulation shows that the formation of the motion error with liner or second phase term gives rise to the image defocus and distortion. The magnitude of motion error poses changes in the range gate drift. When the motion error exceeds a range bin during synthetic time, resample should be taken into consideration; the resample inaccuracy within one bin does not have impact on azimuth focus, but the signal amplitude, so resample is necessary and important in motion compensation

    @InProceedings{guoyongmeiChenhaoHongwenMaoshiyi2000:MoComp,
    Title = {{{Resample in the first order motion compensation of real-time SAR processor}}},
    Author = {Guoyongmei and Chenhao and Hongwen and Maoshiyi},
    Booktitle = {5th International Conference on Signal Processing Proceedings, 2000. WCCC-ICSP 2000},
    Doi = {10.1109/ICOSP.2000.893458},
    Pages = {1830--1833},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=893458&isnumber=19317},
    Volume = {3},
    Year = {2000},
    Abstract = {The resample problem in the first order motion compensation of real-time SAR processor is presented. The motion error model is properly established, and the simulation shows that the formation of the motion error with liner or second phase term gives rise to the image defocus and distortion. The magnitude of motion error poses changes in the range gate drift. When the motion error exceeds a range bin during synthetic time, resample should be taken into consideration; the resample inaccuracy within one bin does not have impact on azimuth focus, but the signal amplitude, so resample is necessary and important in motion compensation},
    Keywords = {SAR Processsing, Airborne SAR, Motion Compensation, MoComp, airborne radar, error compensation, image sampling, motion compensation, radar imaging, real-time systems, synthetic aperture radarSAR image, airborne radar, azimuth focus, first order motion compensation, image defocus, image distortion, motion error model, phase errors, real-time SAR processor, resample problem, signal amplitude, synthetic aperture radar},
    Owner = {ofrey},
    Pdf = {../../../docs/guoyongmeiChenhaoHongwenMaoshiyi2000.pdf} 
    }
    


  5. Leif J. Harcke, Howard A. Zebker, R.F. Jurgens, and M.A. Slade. Delay-Doppler radar imaging of ``overspread'' planets. In Proc. IEEE Int. Geosci. Remote Sens. Symp., volume 1, pages 284-286, 2000. Keyword(s): delay-Doppler radar imaging, high resolution imaging, measurement technique, overspread planet, planetary radar astronomy, processing method, radar astronomy, radar signal processing, radioastronomy, rapidly rotating object, signal design, Doppler radar, asteroids, planetary surfaces, planets, radar applications, radar imaging, radar signal processing, radioastronomical techniques.
    Abstract: The authors review the current state of signal design and processing methods for planetary radar astronomy. Extensions to these techniques required for high resolution imaging of rapidly rotating solar system objects are discussed

    @InProceedings{harckeZebkerJurgensSlade2000,
    Title = {Delay-Doppler radar imaging of ``overspread'' planets},
    Author = {Harcke, Leif J. and Zebker, Howard A. and Jurgens, R.F. and Slade, M.A.},
    Booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    Doi = {10.1109/IGARSS.2000.860493},
    Pages = {284-286},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=860493},
    Volume = {1},
    Year = {2000},
    Abstract = {The authors review the current state of signal design and processing methods for planetary radar astronomy. Extensions to these techniques required for high resolution imaging of rapidly rotating solar system objects are discussed},
    Keywords = {delay-Doppler radar imaging;high resolution imaging;measurement technique;overspread planet;planetary radar astronomy;processing method;radar astronomy;radar signal processing;radioastronomy;rapidly rotating object;signal design;Doppler radar;asteroids;planetary surfaces;planets;radar applications;radar imaging;radar signal processing;radioastronomical techniques},
    Pdf = {../../../docs/harckeZekberJurgensSlade2000.pdf} 
    }
    


  6. Lance M. Kaplan, Seung-Mok Oh, Matthew C. Cobb, and James H. McClellan. Error Analysis for Quadtree Image Formation. In International Conference on Image Processing, ICIP 2000, volume 1, pages 717-720, September 2000. Keyword(s): SAR Processing, Back-Projection, Quadtree Processing, Error Analysis, Ultra-Wideband SAR.
    Abstract: The quadtree image formation technique is a computationally efficient approximation to standard backprojection. Where the computational load of backprojection is O(N^3) for N sensors forming an N?N image, the quadtree method uses a divide-and-conquer strategy similar to the fast Fourier transform (FFT) to reduce the computational load down to O(N^2*log(N)). However, the quadtree introduces errors in the relative time shifts used to focus pulses. These errors reduce the signal gain in the mainlobe response for isotropic point-like targets. In addition, the oscillations of the sidelobes increase from stage to stage. This paper develops performance bounds for the mainlobe losses under far field conditions and relates these bounds to the slow-time Nyquist rate

    @InProceedings{kaplanEtAllErrorAnaly00:Backproj,
    Title = {{Error Analysis for Quadtree Image Formation}},
    Author = {Lance M. Kaplan and Seung-Mok Oh and Matthew C. Cobb and James H. McClellan},
    Booktitle = {International Conference on Image Processing, ICIP 2000},
    Month = sep,
    Pages = {717-720},
    Volume = {1},
    Year = {2000},
    Abstract = {The quadtree image formation technique is a computationally efficient approximation to standard backprojection. Where the computational load of backprojection is O(N^3) for N sensors forming an N?N image, the quadtree method uses a divide-and-conquer strategy similar to the fast Fourier transform (FFT) to reduce the computational load down to O(N^2*log(N)). However, the quadtree introduces errors in the relative time shifts used to focus pulses. These errors reduce the signal gain in the mainlobe response for isotropic point-like targets. In addition, the oscillations of the sidelobes increase from stage to stage. This paper develops performance bounds for the mainlobe losses under far field conditions and relates these bounds to the slow-time Nyquist rate},
    Keywords = {SAR Processing, Back-Projection, Quadtree Processing, Error Analysis, Ultra-Wideband SAR},
    Pdf = {../../../docs/kaplanEtAllErrorAnalysis00.pdf} 
    }
    


  7. Lance M. Kaplan, Seung-Mok Oh, and James H. McClellan. Detection of Broadside Targets During Image Formation Using a Quadtree Approach. In The Record of the 2000 IEEE Radar Conference, pages 104-109, May 2000. Keyword(s): SAR Processing, Back-Projection, Quadtree Processing, Ultra-Wideband SAR, Boom-SAR, Multiscale Detection.
    Abstract: The military is interested in using ultra-wideband (UWB) synthetic aperture radar (SAR) systems to detect ground targets. Standard automatic target detection methods search the entire scene for regions of interest (ROI) after image formation. In order to save computations, we introduce a multiscale detection algorithm that uses partially processed radar data during the intermediate stages of a quadtree-based backprojection image formation algorithm. When the detector accrues enough information to determine that a patch of ground is free of potential targets, it then cues the image former to terminate the processing that would further resolve that patch. The detector combines a feature that estimates the coherent signal to noise ratio with another feature that exploits the broadside flash scattering phenomenon. The new approach is evaluated over a measured database generated by the ARL Boom-SAR radar.

    @InProceedings{kaplanEtAllDet00:Backproj,
    Title = {{Detection of Broadside Targets During Image Formation Using a Quadtree Approach}},
    Author = {Lance M. Kaplan and Seung-Mok Oh and James H. McClellan},
    Booktitle = {The Record of the 2000 IEEE Radar Conference},
    Month = May,
    Pages = {104-109},
    Year = {2000},
    Abstract = {The military is interested in using ultra-wideband (UWB) synthetic aperture radar (SAR) systems to detect ground targets. Standard automatic target detection methods search the entire scene for regions of interest (ROI) after image formation. In order to save computations, we introduce a multiscale detection algorithm that uses partially processed radar data during the intermediate stages of a quadtree-based backprojection image formation algorithm. When the detector accrues enough information to determine that a patch of ground is free of potential targets, it then cues the image former to terminate the processing that would further resolve that patch. The detector combines a feature that estimates the coherent signal to noise ratio with another feature that exploits the broadside flash scattering phenomenon. The new approach is evaluated over a measured database generated by the ARL Boom-SAR radar.},
    Keywords = {SAR Processing, Back-Projection, Quadtree Processing, Ultra-Wideband SAR, Boom-SAR, Multiscale Detection},
    Pdf = {../../../docs/kaplanEtAllDet00.pdf} 
    }
    


  8. Yunjin Kim and Jakob van Zyl. Overview of Polarimetric Interferometry. In Aerospace Conference Proceedings, 2000 IEEE, volume 3, pages 231-236, 2000. Keyword(s): SAR Processing, radar polarimetry, radiowave interferometry, synthetic aperture radar, SAR interferometry, InSAR, SAR polarimetric interferometry, SAR polarimetry, synthetic aperture radar, Pol-InSAR.
    Abstract: SAR (Synthetic Aperture Radar) interferometry has enabled twoimportant science applications: surface change detection and topographicmapping. SAR interferometry is sensitive to the location of the imagedarea and the scattering geometry. SAR polarimetry makes use of thepolarization dependent scattering response of each pixel within theimaged area. The polarimetric response is highly sensitive to thescattering mechanism of a pixel. S.R. Cloude and K.P. Papathanassioufirst published the formulation of polarimetric interferometry thatcombines both SAR interferometry and SAR polarimetry. The main purposeof using polarimetric interferometry is to extract scattering mediuminformation that may be difficult to obtain from scalar interferometry.Even though the formulation and initial demonstrations appear to be verypromising, potential applications of polarimetric interferometry canonly be verified by comparing polarimetric interferometry signatureswith ground truth data. In this talk, we present the theory andimplementation of SAR polarimetric interferometry. Especially, we reviewSAR polarimetry, SAR interferometry, and SAR polarimetric interferometryin a unified manner. In addition, a new calibration technique suitablefor polarimetric interferometry is suggested in this paper

    @InProceedings{vanZylKim00:Polarimetry,
    Title = {Overview of Polarimetric Interferometry},
    Author = {Kim, Yunjin and van Zyl, Jakob},
    Booktitle = {Aerospace Conference Proceedings, 2000 IEEE},
    Pages = {231--236},
    Url = {http://ieeexplore.ieee.org/iel5/7042/19038/00879850.pdf},
    Volume = {3},
    Year = {2000},
    Abstract = {SAR (Synthetic Aperture Radar) interferometry has enabled twoimportant science applications: surface change detection and topographicmapping. SAR interferometry is sensitive to the location of the imagedarea and the scattering geometry. SAR polarimetry makes use of thepolarization dependent scattering response of each pixel within theimaged area. The polarimetric response is highly sensitive to thescattering mechanism of a pixel. S.R. Cloude and K.P. Papathanassioufirst published the formulation of polarimetric interferometry thatcombines both SAR interferometry and SAR polarimetry. The main purposeof using polarimetric interferometry is to extract scattering mediuminformation that may be difficult to obtain from scalar interferometry.Even though the formulation and initial demonstrations appear to be verypromising, potential applications of polarimetric interferometry canonly be verified by comparing polarimetric interferometry signatureswith ground truth data. In this talk, we present the theory andimplementation of SAR polarimetric interferometry. Especially, we reviewSAR polarimetry, SAR interferometry, and SAR polarimetric interferometryin a unified manner. In addition, a new calibration technique suitablefor polarimetric interferometry is suggested in this paper},
    Keywords = {SAR Processing, radar polarimetry, radiowave interferometry, synthetic aperture radar, SAR interferometry, InSAR, SAR polarimetric interferometry, SAR polarimetry, synthetic aperture radar, Pol-InSAR},
    Owner = {ofrey},
    Pdf = {../../../docs/vanZylKim00.pdf},
    Timestamp = {2006.03.24} 
    }
    


  9. J. C. Kirk, R. Lefevre, R. Van Daalen Wetters, D. Woods, and B. Sullivan. Signal based motion compensation (SBMC). In Record of the IEEE 2000 International Radar Conference, pages 463-468, May 2000. Keyword(s): SAR Processing, Autofocus, motion compensation, radar theory, radar signal processing, aircraft navigation, jamming, air traffic control, signal based motion compensation, SAR, down range compensation, cross range compensation, radar signal, platform motion, aircraft navigation, autofocus performance, navigation system performance degradation, component failure, GPS jamming, Motion compensation, Costs, Robustness, Motion measurement, Radar measurements, Airborne radar, Aircraft navigation, System performance, Degradation, Global Positioning System.
    Abstract: Signal based motion compensation (SBMC) is an enabling technology for low cost SAR applications as well as an enhancement for more robust SAR applications. SBMC involves down range and cross range compensation for platform motion with motion compensation signals derived entirely from radar signal based measurements. It is an alternative to motion measurement sensor (MMS)-based motion compensation and a next step growth from autofocus. A very robust SBMC algorithm has been developed and demonstrated on simulated data and real radar data provided by actual radars. The algorithm is tuned to a particular radar and adapted to any level of aircraft navigation system. This SBMC approach will enable a low cost SAR capability to be provided for budget minded applications. Alternately, it can also be applied to high performance SAR systems for improved capability. It will extend current MMS motion compensation and autofocus performance and provide a backup capability to compensate for navigation system performance degradation, such as from component failure or GPS jamming.

    @InProceedings{kirkLefevreVanDaalenWettersWoodsSullivanIEEERadarConf2000SignalBasedMotionCompensation,
    author = {J. C. {Kirk} and R. {Lefevre} and R. {Van Daalen Wetters} and D. {Woods} and B. {Sullivan}},
    booktitle = {Record of the IEEE 2000 International Radar Conference},
    title = {Signal based motion compensation {(SBMC)}},
    year = {2000},
    month = {May},
    pages = {463-468},
    abstract = {Signal based motion compensation (SBMC) is an enabling technology for low cost SAR applications as well as an enhancement for more robust SAR applications. SBMC involves down range and cross range compensation for platform motion with motion compensation signals derived entirely from radar signal based measurements. It is an alternative to motion measurement sensor (MMS)-based motion compensation and a next step growth from autofocus. A very robust SBMC algorithm has been developed and demonstrated on simulated data and real radar data provided by actual radars. The algorithm is tuned to a particular radar and adapted to any level of aircraft navigation system. This SBMC approach will enable a low cost SAR capability to be provided for budget minded applications. Alternately, it can also be applied to high performance SAR systems for improved capability. It will extend current MMS motion compensation and autofocus performance and provide a backup capability to compensate for navigation system performance degradation, such as from component failure or GPS jamming.},
    doi = {10.1109/RADAR.2000.851878},
    file = {:kirkLefevreVanDaalenWettersWoodsSullivanIEEERadarConf2000SignalBasedMotionCompensation.pdf:PDF},
    keywords = {SAR Processing, Autofocus, motion compensation;radar theory;radar signal processing;aircraft navigation;jamming;air traffic control;signal based motion compensation;SAR;down range compensation;cross range compensation;radar signal;platform motion;aircraft navigation;autofocus performance;navigation system performance degradation;component failure;GPS jamming;Motion compensation;Costs;Robustness;Motion measurement;Radar measurements;Airborne radar;Aircraft navigation;System performance;Degradation;Global Positioning System},
    owner = {ofrey},
    
    }
    


  10. J.M. Lopez-Sanchez, J. Fortuny, A.J. Sieber, L. Sagues, M. Bara, X. Fabregas, and A. Broquetas. Experimental comparison of different scattering mechanism selections for vegetation height retrieval by POLINT. In Geoscience and Remote Sensing Symposium, 2000. Proceedings. IGARSS 2000. IEEE 2000 International, volume 1, pages 138-140, July 2000.
    @InProceedings{Lopez-Sanchez2000,
    Title = {Experimental comparison of different scattering mechanism selections for vegetation height retrieval by POLINT},
    Author = {Lopez-Sanchez, J.M. and Fortuny, J. and Sieber, A.J. and Sagues, L. and Bara, M. and Fabregas, X. and Broquetas, A.},
    Booktitle = {Geoscience and Remote Sensing Symposium, 2000. Proceedings. IGARSS 2000. IEEE 2000 International},
    Doi = {10.1109/IGARSS.2000.860447},
    Month = jul,
    Pages = {138--140},
    Volume = {1},
    Year = {2000},
    Owner = {ofrey},
    Timestamp = {2009.03.05} 
    }
    


  11. Jordi J. Mallorqui, M. Bara, and A. Broquetas. Sensitivity equations and calibration requirements on airborne interferometry. In Proc. IEEE Int. Geosci. Remote Sens. Symp., volume 6, pages 2739-2741, July 2000.
    @InProceedings{Mallorqui2000,
    Title = {Sensitivity equations and calibration requirements on airborne interferometry},
    Author = {Mallorqui, Jordi J. and Bara, M. and Broquetas, A.},
    Booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    Doi = {10.1109/IGARSS.2000.859699},
    Month = jul,
    Pages = {2739-2741},
    Volume = {6},
    Year = {2000},
    Owner = {ofrey},
    Timestamp = {2009.03.05} 
    }
    


  12. David Small, Stefan Biegger, and Daniel Nüesch. Automated tie point retrieval through heteromorphic image simulation for spaceborne SAR sensors. In Proc. ESA ERS-ENVISAT Symp., Gothenburg, Sweden, 2000. Keyword(s): SAR Processing, Radiometric Calibration, Automated Tiepoint Retrieval.
    @InProceedings{smallBieggerNuesch2000:AutomaticTiePointRetrieval,
    Title = {Automated tie point retrieval through heteromorphic image simulation for spaceborne SAR sensors},
    Author = {David Small and Stefan Biegger and Daniel N\"uesch},
    Booktitle = {Proc. ESA ERS-ENVISAT Symp.},
    Year = {2000},
    Address = {Gothenburg, Sweden},
    Keywords = {SAR Processing, Radiometric Calibration, Automated Tiepoint Retrieval},
    Owner = {ofrey} 
    }
    


  13. David Small, Stefan Biegger, and Daniel Nüesch. The Topology of SAR Imagery in Rough Terrain. In Proc. of EUSAR 2000 - 3rd European Conference on Synthetic Aperture Radar, 2000. Keyword(s): SAR Processing, SAR, Calibration, Terrain, DEM, Image Simulation, Terrain-Geocoding, Topology, Heteromorphism.
    @InProceedings{smallBieggerNueschEUSAR2000:ImgRoughTerrain,
    Title = {The Topology of SAR Imagery in Rough Terrain},
    Author = {David Small and Stefan Biegger and Daniel N{\"u}esch},
    Booktitle = {Proc. of EUSAR 2000 - 3rd European Conference on Synthetic Aperture Radar},
    Year = {2000},
    Keywords = {SAR Processing, SAR, Calibration, Terrain, DEM, Image Simulation, Terrain-Geocoding, Topology, Heteromorphism},
    Owner = {ofrey},
    Pdf = {../../../docs/smallBieggerNueeschEUSAR2000.pdf},
    Timestamp = {2006.03.27} 
    }
    


  14. Mehrdad Soumekh, Gernot Gunther, Mark Linderman, and Ralph Kohler. Digitally-Spotlighted Subaperture SAR Image Formation Using High Performance Computing. In Edmund G. Zelnio, editor, Algorithms for Synthetic Aperture Radar Imagery VII, volume SPIE 4053, pages 260-271, 2000. Keyword(s): SAR Processing, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, RFI Suppression, Subaperture Processing, Parallel Processing, Digital Spotlighting, Slow-Time Upsampling, Alias-free Processing, Real-Time Processing, High Performance Computing, FFTW.
    Abstract: This paper is concerned with the implementation of the SAR wavefront reconstruction algorithm on a high performance computer. For this purpose, the imaging algorithm is reformulated as a coherent processing (spectral combination) of images that are formed from a set of subapertures of the available synthetic aperture. This is achieved in conjunction with extracting the signature of a specific target region (digital spotlighting). Issues that are associated with implementing the algorithm on SMP-HPCs and DMP-HPCs are discussed. The results using the FOPEN P-3 SAR data are provided.

    @InProceedings{SoumekhGuntherLindermanKohler00:Subaperture,
    Title = {{Digitally-Spotlighted Subaperture SAR Image Formation Using High Performance Computing}},
    Author = {Mehrdad Soumekh and Gernot Gunther and Mark Linderman and Ralph Kohler},
    Booktitle = {Algorithms for Synthetic Aperture Radar Imagery VII},
    Editor = {Edmund G. Zelnio},
    Pages = {260-271},
    Url = {http://spiedl.aip.org/vsearch/servlet/VerityServlet?KEY=SPIEDL&smode=strresults&maxdisp=25&possible1=Soumekh%2C+Mehrdad&possible1zone=author&OUTLOG=NO&aqs=true&key=DISPLAY&docID=6&page=0&chapter=0},
    Volume = {SPIE 4053},
    Year = {2000},
    Abstract = {This paper is concerned with the implementation of the SAR wavefront reconstruction algorithm on a high performance computer. For this purpose, the imaging algorithm is reformulated as a coherent processing (spectral combination) of images that are formed from a set of subapertures of the available synthetic aperture. This is achieved in conjunction with extracting the signature of a specific target region (digital spotlighting). Issues that are associated with implementing the algorithm on SMP-HPCs and DMP-HPCs are discussed. The results using the FOPEN P-3 SAR data are provided.},
    Keywords = {SAR Processing, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, RFI Suppression, Subaperture Processing, Parallel Processing, Digital Spotlighting, Slow-Time Upsampling, Alias-free Processing, Real-Time Processing, High Performance Computing, FFTW},
    Pdf = {../../../docs/SoumekhGuntherLindermanKohler00.pdf} 
    }
    


  15. Mehrdad Soumekh, Steve Worrell, Edward G. Zelnio, and Brett Keaffaber. SAR Wavefront Reconstruction Using Motion Compensated Phase History (Polar Format) Data and DPCA-Based GMTI. In Edmund G. Zelnio, editor, Algorithms for Synthetic Aperture Radar Imagery VII, volume SPIE 4053, pages 64-75, 2000. Keyword(s): SAR Processing, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, Polar Format Algorithm, X-Band, Squinted SAR, Motion Compensation, Monopulse SAR, MTI, GMTI.
    Abstract: This paper address the problem of processing an X-band SAR database that was originally intended for processing via a polar format imaging algorithm. In our approach, we use the approximation-free SAR wavefront reconstruction. For this, the measured and motion compensated phase history (polar format) data are processed in a multi-dimensional digital signal processing algorithm that yields alias-free slow-time samples. The resultant database is used for wavefront image formation. The X-band SAR system also provides a two channel along-track monopulse database. The alias-free monopulse SAR data are used in a coherent signal subspace algorithm for Ground Moving Target Indication (GMTI). Results are provided.

    @InProceedings{SoumekhWorrellZelnioKeaffaber00:Wavefront,
    Title = {{SAR Wavefront Reconstruction Using Motion Compensated Phase History (Polar Format) Data and DPCA-Based GMTI}},
    Author = {Mehrdad Soumekh and Steve Worrell and Edward G. Zelnio and Brett Keaffaber},
    Booktitle = {Algorithms for Synthetic Aperture Radar Imagery VII},
    Editor = {Edmund G. Zelnio},
    Pages = {64-75},
    Url = {http://spiedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PSISDG004053000001000064000001&idtype=cvips&gifs=yes},
    Volume = {SPIE 4053},
    Year = {2000},
    Abstract = {This paper address the problem of processing an X-band SAR database that was originally intended for processing via a polar format imaging algorithm. In our approach, we use the approximation-free SAR wavefront reconstruction. For this, the measured and motion compensated phase history (polar format) data are processed in a multi-dimensional digital signal processing algorithm that yields alias-free slow-time samples. The resultant database is used for wavefront image formation. The X-band SAR system also provides a two channel along-track monopulse database. The alias-free monopulse SAR data are used in a coherent signal subspace algorithm for Ground Moving Target Indication (GMTI). Results are provided.},
    Keywords = {SAR Processing, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, Polar Format Algorithm, X-Band, Squinted SAR, Motion Compensation, Monopulse SAR, MTI, GMTI},
    Pdf = {../../../docs/SoumekhWorrellZelnioKeaffaber00.pdf} 
    }
    


  16. David A. Yocky and Charles V. Jakowatz. Two-target height effects on interferometric synthetic aperture radar coherence. In Edmund G. Zelnio, editor, , volume 4053, pages 102-108, 2000. SPIE. Keyword(s): SAR Processing, SAR Tomography, InSAR, SAR Interferometry, Polar Format Algorithm, PFA, Spotlight SAR, Spotlight-mode data.
    @Conference{yockyJakowatzTwoTargetsInSAR2000,
    author = {David A. Yocky and Charles V. Jakowatz, Jr.},
    title = {Two-target height effects on interferometric synthetic aperture radar coherence},
    year = {2000},
    editor = {Edmund G. Zelnio},
    volume = {4053},
    number = {1},
    pages = {102-108},
    publisher = {SPIE},
    doi = {10.1117/12.396320},
    file = {:yockyJakowatzTwoTargetsInSAR2000.pdf:PDF},
    journal = {Algorithms for Synthetic Aperture Radar Imagery VII},
    keywords = {SAR Processing, SAR Tomography, InSAR, SAR Interferometry, Polar Format Algorithm, PFA, Spotlight SAR, Spotlight-mode data},
    location = {Orlando, FL, USA},
    owner = {ofrey},
    pdf = {../../../docs/yockyJakowatzTwoTargetsInSAR2000.pdf},
    url = {http://link.aip.org/link/?PSI/4053/102/1},
    
    }
    


BACK TO INDEX BACK TO OTHMAR FREY'S HOMEPAGE


Disclaimer:

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.
Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright.

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 .


This document was translated from BibTEX by bibtex2html