Results 1  10
of
26
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 ..."
Abstract

Cited by 43 (1 self)
 Add to MetaCart
(Show Context)
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.
A new polarimetric classification approach evaluated on agricultural crops
 Proc of ESA POLINSAR 2003 Workshop, Frascati, Italy ª Copyright QinetiQ Ltd 2003
"... Statistical properties of the polarimetric backscatter behaviour for a single homogeneous area are described by the Wishart distribution or its marginal distributions. These distributions do not necessarily well describe the statistics for a collection of homogeneous areas of the same class because ..."
Abstract

Cited by 15 (4 self)
 Add to MetaCart
(Show Context)
Statistical properties of the polarimetric backscatter behaviour for a single homogeneous area are described by the Wishart distribution or its marginal distributions. These distributions do not necessarily well describe the statistics for a collection of homogeneous areas of the same class because of variation in, for example, biophysical parameters. Using KolmogorovSmirnov (KS) tests of fit it is shown that, for example, the Beta distribution is a better descriptor for the coherence magnitude, and the lognormal distribution for the backscatter level. An evaluation is given for a number of agricultural crop classes, grasslands and fruit tree plantations at the Flevoland test site, using an AirSAR (C, L and Pband polarimetric) image of 3 July 1991. A new reversible transform of the covariance matrix into backscatter intensities will be introduced in order to describe the full polarimetric target properties in a mathematically alternative way, allowing for the development of simple, versatile and robust classifiers. Moreover, it allows for polarimetric image segmentation using conventional approaches. The effect of azimuthally asymmetric backscatter behaviour on the classification results is discussed. Several models are proposed and results are compared with results from literature for the same test site. It can be concluded that the introduced classifiers perform very well, with levels of accuracy for this test site of 90.4 % for Cband, 88.7 % for Lband and 96.3 % for the combination of C and Lband. 1.
Polarimetric scattering and emission properties of targets with reflection symmetry
 Radio Sci
, 1994
"... Abstract. This paper investigates the symmetry of polarimetric scattering and emission coefficients of media with reflection symmetry. A reflection operator is defined and is used to create the images of electromagnetic fields and sources. The image fields satisfy Maxwell's equations, meaning t ..."
Abstract

Cited by 13 (1 self)
 Add to MetaCart
Abstract. This paper investigates the symmetry of polarimetric scattering and emission coefficients of media with reflection symmetry. A reflection operator is defined and is used to create the images of electromagnetic fields and sources. The image fields satisfy Maxwell's equations, meaning that Maxwell's equations are invariant under the described reflection operations. By applying the reflection operations to media with reflection symmetry, the symmetry properties of the Stokes parameters, characterizing the polarization state of thermal emissions, are shown to agree with existing experimental data. The first two Stokes parameters are symmetric with respect to the reflection plane, while the third and fourth Stokes parameters have odd symmetry. In active remote sensing, the symmetry properties of the polarimetric scattering matrix elements of deterministic targets and the polarimetric covariance matrix elements of random media or distributed targets are examined. For deterministic targets, the crosspolarized responses are odd functions with respect to the symmetry direction, whereas the copolarized responses are even functions. For distributed targets or random media, it is found that the correlations of copolarized and crosspolarized responses are antisymmetric with respect to the reflection plane, while the other covariance matrix elements are symmetric. Consequently, in the cases of backscatter, the copolarized and crosspolarized components are completely uncorrelated when the incidence direction is on the symmetry plane. The derived symmetry properties of polarimetric backscattering coefficients agree with the predictions of a twoscale surface scattering model and existing sea surface HH and VV backscatter data. Finally, the conditions for a general type of media, i.e., bianisotropic media, to be reflection symmetric are examined. 1.
Investigation of the capability of the Compact Polarimetry mode to Reconstruct Full Polarimetry mode using RADARSAT2 data
"... Recently, there has been growing interest in dualpol systems that transmit one polarization and receive two polarizations. Souyris et al. proposed a DP mode called compact polarimetry (CP) which is able to reduce the complexity, cost, mass, and data rate of a SAR system while attempting to maintain ..."
Abstract

Cited by 2 (1 self)
 Add to MetaCart
(Show Context)
Recently, there has been growing interest in dualpol systems that transmit one polarization and receive two polarizations. Souyris et al. proposed a DP mode called compact polarimetry (CP) which is able to reduce the complexity, cost, mass, and data rate of a SAR system while attempting to maintain many capabilities of a fully polarimetric system. This paper provides a comparison of the information content of full quadpol data and the pseudo quadpol data derived from compact polarimetric SAR modes. A pseudocovariance matrix can be reconstructed following Souyris’s approach and is shown to be similar to the full polarimetric (FP) covariance matrix. Both the polarimetric signatures based on the kennaugh matrix and the Freeman and Durden decomposition in the context of this compact polarimetry mode are explored. The Freeman and Durden decomposition is used in our study because of its direct relationship to the reflection symmetry. We illustrate our results by using the polarimetric SAR images of Algiers city in Algeria acquired by the RadarSAT2 in Cband. 1.
ASSESSMENT OF LBAND SAR DATA AT DIFFERENT POLARIZATION COMBINATIONS FOR CROP AND OTHER LANDUSE CLASSIFICATION
"... Abstract—In the present study evaluation of Lband SAR data at different polarization combinations in linear, circular as well as hybrid polarimetric imaging modes for crop and other landuse classifications has been carried out. Fullpolarimetric radar data contains all the scattering information fo ..."
Abstract

Cited by 2 (1 self)
 Add to MetaCart
(Show Context)
Abstract—In the present study evaluation of Lband SAR data at different polarization combinations in linear, circular as well as hybrid polarimetric imaging modes for crop and other landuse classifications has been carried out. Fullpolarimetric radar data contains all the scattering information for any arbitrary polarization state, hence data of any combination of transmit and receive polarizations can be synthesized, mathematically from fullpolarimetric data. Circular and various modes of hybrid polarimetric data (where the transmitter polarization is either circular or orientated at 45 ◦ , called π/4 and the receivers are at horizontal and vertical polarizations with respect to the radar line of sight) were synthesized (simulated) from ALOSPALSAR fullpolarimetric data of 14th December 2008 over central state farm central latitude and longitude 29◦15 ′ N/75◦43 ′ E and bounds for northwest corner is 29◦24 ′ N/75◦37 ′ E and southeast corner is 29◦07 ′ N/75◦48 ′ E in Hisar, Haryana (India) Supervised classification was conducted for crops and few other landuse classes based on ground truth measurements using maximumlikelihood distance measures derived from the complex Wishart distribution of SAR data at various polarization combinations. It has been observed that linear fullpolarimetric data showed maximum classification accuracy (92%) followed by circularfull (89%) and circulardual polarimetric data (87%), which was followed by hybrid polarimetric data (73–75%) and then linear dual polarimetric data (63–71%). Among the linear dual polarimetric data, copolarization complex data showed better
ASSESSING NATURAL DISASTER IMPACTS AND RECOVERY USING MULTIFREQUENCY, FULLYPOLARIMETRIC SYNTHETIC APERTURE RADAR (SAR)
"... Many natural disasters involving landslides, volcanic eruptions, fires, or floods entail terrain resurfacing, followed by subsequent recovery. Modern satellite and airborne remote sensing technologies, which combine broad spatial coverage and high spatial resolution with timesequential site revisit ..."
Abstract
 Add to MetaCart
(Show Context)
Many natural disasters involving landslides, volcanic eruptions, fires, or floods entail terrain resurfacing, followed by subsequent recovery. Modern satellite and airborne remote sensing technologies, which combine broad spatial coverage and high spatial resolution with timesequential site revisit capability, can provide important information on the extent and duration of major landscape disturbance. In humid climate settings, these hazards temporarily remove or replace a natural vegetation cover and in doing so, modify the physical properties of the land surface. In optical remote sensing, removal of vegetation alters surface albedo in the visible near infrared (VNIR) waveband, particularly the high reflectance from vegetation in the NIR. For SAR remote sensing, removal of vegetation cover causes a change in dominant microwave scattering mechanism for the areas affected. SAR has operational advantages over optical sensors for rapid disaster assessment because of its day/night acquisition capability, the ability to “see through ” smoke, clouds and dust, and the sidelooking viewing geometry, which is an advantage whenever data collection directly above the site would prove dangerous. We show how multifrequency, fullypolarimetric airborne SAR data can be “inverted ” for parameters that reflect scattering mechanism signatures diagnostic of different surface cover types. We apply a uniform approach to map landslides resulting from the 1999 Mw 7.6 ChiChi earthquake in Taiwan and volcanic flows from the major 1996 eruption of Manam volcano in Papua New Guinea. In addition, earlier work has shown that multifrequency SAR polarimetric backscatter is sensitive to total aboveground biomass. This attribute can be exploited to calculate vegetation loss during a disaster and for assessment of regrowth during the recovery phase. 1
Open Archive TOULOUSE Archive Ouverte (OATAO)
"... OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an authordeposited version published in: ..."
Abstract
 Add to MetaCart
(Show Context)
OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an authordeposited version published in:
signatures of sea ice Part I: Theoretical model
"... this paper provides a link between the observed ..."
GROUND—AGRICULTURE SEPARATION BY MEANS OF POLINSAR
"... Abstract — POLINSAR coherence is a sensitive parameter for both, the vertical structure of the resolution cell and the types of scattering mechanisms inside the cell. It is being utilized in various areas, including natural media parameter inversion. Different applications have been developed in com ..."
Abstract
 Add to MetaCart
(Show Context)
Abstract — POLINSAR coherence is a sensitive parameter for both, the vertical structure of the resolution cell and the types of scattering mechanisms inside the cell. It is being utilized in various areas, including natural media parameter inversion. Different applications have been developed in combination with the ”Random Volume over Ground ” (RVoG) and the ”Oriented Volume over Ground ” (OVoG) models. The later one expects generally horizontally and vertically oriented volume and surface. Furthermore, the phase shift effects, induced by refractivities inside the vegetation, are neglected. This work analyses these two restrictions and extends the formulation of the OVoG model for the coherency matrices to the propagation effects caused by differential refractivity and orientation effects of the vegetation and the surface. Based on this model, its applicability for monitoring sub– vegetation parameters is investigated. For this purpose, the ground to volume coherence ratio is maximized and ground sensitive parameters are extracted. To evaluate the results, a coherent volume over ground model simulation has been developed. Initial experimental results from the simulations will be presented. I.
Fitting
"... a twocomponent scattering model to polarimetric SAR data from forests ..."
(Show Context)