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A test statistic in the complex Wishart distribution and its application to change detection in polarimetric SAR data
 IEEE Trans. Geosci. Remote Sensing
, 2003
"... Abstract—When working with multilook fully polarimetric synthetic aperture radar (SAR) data, an appropriate way of representing the backscattered signal consists of the socalled covariance matrix. For each pixel, this is a 3 3 Hermitian positive definite matrix that follows a complex Wishart distri ..."
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Abstract—When working with multilook fully polarimetric synthetic aperture radar (SAR) data, an appropriate way of representing the backscattered signal consists of the socalled covariance matrix. For each pixel, this is a 3 3 Hermitian positive definite matrix that follows a complex Wishart distribution. Based on this distribution, a test statistic for equality of two such matrices and an associated asymptotic probability for obtaining a smaller value of the test statistic are derived and applied successfully to change detection in polarimetric SAR data. In a case study, EMISAR Lband data from April 17, 1998 and May 20, 1998 covering agricultural fields near Foulum, Denmark are used. Multilook full covariance matrix data, azimuthal symmetric data, covariance matrix diagonalonly data, and horizontal–horizontal (HH), vertical–vertical (VV), or horizontal–vertical (HV) data alone can be used. If applied to HH, VV, or HV data alone, the derived test statistic reduces to the wellknown gamma likelihoodratio test statistic. The derived test statistic and the associated significance value can be applied as a line or edge detector in fully polarimetric SAR data also. Index Terms—Covariance matrix test statistic, EMISAR, radar applications, radar polarimetry, remote sensing change detection. I.
CFAR Edge Detector for Polarimetric SAR Images
 IEEE Transactions on Geoscience and Remote Sensing
, 2003
"... Abstract—Finding the edges between different regions in an image is one of the fundamental steps of image analysis, and several edge detectors suitable for the special statistics of synthetic aperture radar (SAR) intensity images have previously been developed. In this paper, a new edge detector for ..."
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Abstract—Finding the edges between different regions in an image is one of the fundamental steps of image analysis, and several edge detectors suitable for the special statistics of synthetic aperture radar (SAR) intensity images have previously been developed. In this paper, a new edge detector for polarimetric SAR images is presented using a newly developed test statistic in the complex Wishart distribution to test for equality of covariance matrices. The new edge detector can be applied to a wide range of SAR data from singlechannel intensity data to multifrequency and/or multitemporal polarimetric SAR data. By simply changing the parameters characterizing the test statistic according to the applied SAR data, constant falsealarm rate detection is always obtained. An adaptive filtering scheme is presented, and the distributions of the detector are verified using simulated polarimetric SAR images. Using SAR data from the Danish airborne polarimetric SAR, EMISAR, it is demonstrated that superior edge detection results are obtained using polarimetric and/or multifrequency data compared to using only intensity data. Index Terms—Complex Wishart distribution, edge detection, polarimetry, synthetic aperture radar (SAR), Wishart likelihoodratio
Electromagnetic scattering from grassland: Part I, A fully coherent scattering model
 IEEE Transactions on Geoscience and Remote Sensing
, 2000
"... Abstract—The validity of a coherent, grassland scattering model is determined by comparing the model predictions with direct measurements of a representative grass canopy. A wheat field was selected as the test target, and polarimetric, multifrequency backscattering data were collected over an entir ..."
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Abstract—The validity of a coherent, grassland scattering model is determined by comparing the model predictions with direct measurements of a representative grass canopy. A wheat field was selected as the test target, and polarimetric, multifrequency backscattering data were collected over an entire growing season, along with a complete set of groundtruth data. The Lband measured data demonstrated a strong dependence on azimuthal look direction in relation to the row direction of the wheat. The Cband measurements likewise showed an interesting backscattering response, wherein H actually increased with incidence angle for many cases. The coherent scattering model provides backscattering data that match and predict these measured data and most of the other measured data well. The model shows that at Lband, the incoherent scattering power alone is insufficient for predicting the measured results, as the coherent terms can dominate the total scattered energy. Additionally, the model, which accounts for this nonuniform illumination of the wheat elements, demonstrates the peculiar data observed for Cband. Likewise, it is demonstrated that the fidelity used to model grass constituents (e.g., curvature) is required to match the scattering measurements accurately. Index Terms—Microwave scattering from grasslands, vegetation scattering measurements. I.
Spectral Clustering of Polarimetric SAR Data with WishartDerived Distance
 Measures Proc. Intl. Workshop on Science and Applications of SAR Polarimetry and Polarimetric Interferometry (POLinSAR2007
, 2007
"... This paper presents a new spectral clustering algorithm, which is specially tailored for segmentation of polarimetric SAR images. This is accomplished by use of certain pairwise distance measures between pixels. The measures are derived from the complex Wishart distribution, and capture the statisti ..."
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This paper presents a new spectral clustering algorithm, which is specially tailored for segmentation of polarimetric SAR images. This is accomplished by use of certain pairwise distance measures between pixels. The measures are derived from the complex Wishart distribution, and capture the statistical information contained in the coherency matrix. We demonstrate how the pairwise distances are transformed into an affinity matrix, whose eigendecomposition determines the optimal partitioning of pixels. We further show that the obtained clustering provides an improved initialization of the classical unsupervised Wishart classifier, and that the entire classification can also be performed in a kernel induced feature space. The algorithms are tested on crop classification with promising results. 1
LandCover Mapping Using Airborne Polarimetric SAR
"... this paper is to simulate the performance of satellite SAR systems, like ERS and ENVISAT, using data from an airborne polarimetric SAR ..."
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this paper is to simulate the performance of satellite SAR systems, like ERS and ENVISAT, using data from an airborne polarimetric SAR
q 2000 American Meteorological Society The Effects of ThreeBody Scattering on Differential Reflectivity Signatures
, 1998
"... Effects of threebody scattering on reflectivity signatures at S and C bands can be seen on the back side of large reflectivity storm cores that contain hail. The fingerlike protrusions of elevated reflectivity have been termed flare echoes or ‘‘hail spikes.’ ’ Threebody scattering occurs when radi ..."
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Effects of threebody scattering on reflectivity signatures at S and C bands can be seen on the back side of large reflectivity storm cores that contain hail. The fingerlike protrusions of elevated reflectivity have been termed flare echoes or ‘‘hail spikes.’ ’ Threebody scattering occurs when radiation from the radar scattered toward the ground is scattered back to hydrometeors, which then scatter some of the radiation back to the radar. Threebody scatter typically causes differential reflectivity to be very high at high elevations and to be negative at lower elevations at the rear of the storm core. This paper describes a model that can simulate the essential features of the threebody scattering that has been observed in hailstorms. The model also shows that threebody scatter can significantly affect the polarimetric ZDR (differential reflectivity) radar signatures in hailshafts at very low elevation and thus is a possible explanation of the frequently reported negative ZDR signatures in hailshafts near ground. 1.
P12R.2 ANTENNA SYSTEM REQUIREMENT FOR DUAL POLARIZATION RADAR DESIGN IN HYBRID MODE OF OPERATION
"... Dualpolarization radar measurements are usually acquired in a pair of orthogonal polarization states. Currently, two operation modes are usually ..."
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Dualpolarization radar measurements are usually acquired in a pair of orthogonal polarization states. Currently, two operation modes are usually
Polarimetric Edge Detector based on the complex Wishart distribution
"... Abstract A new edge detector for polarimetric SAR data has been developed. The edge detector is based on a newly developed test statistic for equality of two complex covariance matrices following the complex Wishart distribution and an associated asymptotic probability for the test statistic. The n ..."
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Abstract A new edge detector for polarimetric SAR data has been developed. The edge detector is based on a newly developed test statistic for equality of two complex covariance matrices following the complex Wishart distribution and an associated asymptotic probability for the test statistic. The new polarimetric edge detector provides a constant false alarm rate and it utilizes the full polarimetric information. The edge detector has been applied to polarimetric SAR data from the Danish dualfrequency, airborne polarimetric SAR, EMISAR. The results show clearly an improved edge detection performance for the full polarimetric detector compared to single channel approaches. I.
Youth Forum
"... This paper represents a study on landcover classification using different polarimetric SAR features. The experiment is carried out using C and Lband fully polarimetric EMISAR data acquired on July 5 and 6, 1995 over an agricultural area in Fjärdhundra, near Uppsala, Sweden. The polarimetric featu ..."
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This paper represents a study on landcover classification using different polarimetric SAR features. The experiment is carried out using C and Lband fully polarimetric EMISAR data acquired on July 5 and 6, 1995 over an agricultural area in Fjärdhundra, near Uppsala, Sweden. The polarimetric features investigated are coherency matrix, intensity of both C and Lband SAR, and Cloud decomposition product H(1A) of Lband, and ‘entropy ’ texture of Lband HV intensity image. In order to investigate the performance of the different features, each feature is classified using a classifier that is best suited for the feature based on previous research. H/A/α Wishart unsupervised classification is used for coherency matrix while neural network is applied to six “mean” texture layers of C and L bands fully polarimetric intensity images. The best classification accuracy was achieved using the intensity images combined with H(1A) and ‘entropy ’ texture (overall: 81%; kappa: 0.7). The producer’s accuracy of intensity classification result for forest is 100.0 % which reveals that the H(1A) of Lband is a very good indicator for forest. The ’entropy ’ texture of Lband HV intensity image has the potential to be a good indicator for road with 77.2 % user accuracy, while road is not discriminated in coherency matrix. The results indicate that the supervised classification of the intensity of both C and L bands has a good potential for landcover mapping in this study area. 1.