Journal ArticleDOI
Radiometric slope correction of synthetic-aperture radar images
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TLDR
An algorithm is described to obtain the slope correction from a SAR interferogram, which also enables retrieval of the full scattering geometry, and demonstrates that the spatial resolution and calibration error are adequate for most applications.Abstract:
The brightness in a SAR image is affected by topographic height variations due to (1) the projection between ground and image coordinates, and (2) variations in backscattering coefficient with the local scattering geometry. This paper derives a new equation for (1), i.e. the radiometric slope correction, based on a calibration equation which is invariant under a coordinate transformation. An algorithm is described to obtain the slope correction from a SAR interferogram, which also enables retrieval of the full scattering geometry. Since the SAR image and interferogram are derived from the same data set, there is no need to match the image with the calibration data. There is also no need for phase unwrapping since the algorithm only uses the fringe frequencies. A maximum-likelihood estimator for the fringe frequency is analyzed and the algorithm is illustrated by processing ERS-1 SAR data. The example demonstrates that the spatial resolution and calibration error are adequate for most applications.read more
Citations
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Journal ArticleDOI
Two-dimensional phase unwrapping with use of statistical models for cost functions in nonlinear optimization
Curtis W. Chen,Howard A. Zebker +1 more
TL;DR: This work develops a maximum a posteriori probability (MAP) estimation approach for interferometric radar techniques, and derives an algorithm that approximately maximizes the conditional probability of its phase-unwrapped solution given observable quantities such as wrapped phase, image intensity, and interferogram coherence.
Journal ArticleDOI
Flattening Gamma: Radiometric Terrain Correction for SAR Imagery
TL;DR: The ASAR & PALSAR sensors provide state vectors and timing with higher absolute accuracy than was previously available, allowing them to directly support accurate tie-point-free geolocation and radiometric normalization of their imagery.
Journal ArticleDOI
Polarimetric SAR data compensation for terrain azimuth slope variation
TL;DR: In this paper, the authors proposed two approaches to compensate for the azimuth slope effect for polarimetric SAR (POLSAR) data correction for changes in radar cross sections.
Journal ArticleDOI
Efficiency of crop identification based on optical and SAR image time series
TL;DR: This paper assessed the use of optical and SAR imagery for crop identification in an operational context with a particular emphasis on actual crop diversity and information delivery time.
Journal ArticleDOI
Retrieval of growing stock volume in boreal forest using hyper-temporal series of Envisat ASAR ScanSAR backscatter measurements
Maurizio Santoro,Christian Beer,Oliver Cartus,Christiane Schmullius,Anatoly Shvidenko,Ian McCallum,Urs Wegmüller,Andreas Wiesmann +7 more
TL;DR: In this paper, a multi-temporal combination of individual forest growing stock volume (GSV) estimates can be used to improve the retrieval performance as compared to the single image case.
References
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Book
Microwave Remote Sensing, Active and Passive
TL;DR: In this article, the authors present a model of a MICROWAVE REMOTE SENSING FUNDAMENTALS and RADIOMETRY, which is based on the idea of surface scattering.
Journal ArticleDOI
Decorrelation in interferometric radar echoes
Howard A. Zebker,J. Villasenor +1 more
TL;DR: It is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible and such a technique could provide a global digital terrain map.
Journal ArticleDOI
Single tone parameter estimation from discrete-time observations
D. Rife,R. Boorstyn +1 more
TL;DR: Estimation of the parameters of a single-frequency complex tone from a finite number of noisy discrete-time observations is discussed and appropriate Cramer-Rao bounds and maximum-likelihood estimation algorithms are derived.
Journal ArticleDOI
Topographic mapping from interferometric synthetic aperture radar observations
TL;DR: In this article, the authors reported the production of high-resolution topographic maps derived from interferometric synthetic aperture radar observations of the earth, which is related to the stereo technique in that the terrain is viewed at two different angles.
Journal ArticleDOI
Estimating and interpreting the instantaneous frequency of a signal. II. Algorithms and applications
TL;DR: The concept of instantaneous frequency (IF) is extended to discrete-time signals and methods based on a modeling of the signal phase as a polynomial have been introduced.