The development of a ground based polarimetric SAR interferometer (GB-POLInSAR)

Copyright © 2005 IEE

Application of Polarization Coherence Tomography to GB-POLInSAR Data

Copyright © 2006 IEE

Structural parameter estimation of Australian flora with a ground-based polarimetric radar interferometer

Copyright © 2006 IEE

Detecting depolarized targets using a new geometrical perturbation filter

Target detectors using polarimetry are often focused on single targets, since these can be characterized in a simpler and deterministic way. The algorithm proposed in this paper is aimed at the more difficult problem of partial target detection (i.e. targets with arbitrary degree of polarization). The authors have already proposed a single target detector employing filters based on a geometrical perturbation. In order to enhance the algorithm to the detection of partial targets, a new vector formalism is introduced. The latter is similar to the one exploited for single targets but suitable for complete characterization of partial targets. A new feature vector is generated starting from the covariance matrix, and exploited for the perturbation method. Validation against L-band fully polarimetric airborne E-SAR, and satellite ALOS-PALSAR data and X-band dual polarimetric TerraSAR-X data is provided with significant agreement with the expected results. Additionally, a comparison with the supervised Wishart classifier is presented revealing improvements

A polarimetric target detector using the Huynen fork

The contribution of SAR polarimetry in target detection is described and found to add valuable information. A new target detection methodology is described that makes novel use of the polarization fork of the target. The detector is based on a correlation procedure in the target space, and other target representations (e.g. Huynen parameters or α angle) can be employed. The mathematical formulation is general and can be applied to any kind of single target, however in this paper the detection is optimized for the odd and even-bounces (first two elements of the Pauli scattering vector) and oriented dipoles. Validation against real data shows significant agreement with the expected results based on the theoretical description

Statistical assessment of eigenvector-based target decomposition theorems in radar polarimetry

© 2005 IEEE.Carlos López-Martínez, Eric Pottier and Shane R. Cloud

Model-Based Decomposition of Dual-Pol SAR Data: Application to Sentinel-1

In this study, we advance a new family of model-based decompositions adapted for dual-pol synthetic aperture radar data. These are formulated using the Stokes vector formalism, coupled to mappings from full quad-pol decomposition theory. A generalized model-based decomposition is developed, which allows separation of an arbitrary Stokes vector into partially polarized and polarized wave components. We employ the widely used random dipole cloud as a volume model but, in general, non-dipole options can be used. The cross-polarized phase δ, and the α angle, which is a function of the ratio between wave components, measure the transformation of polarization state on reflection. We apply the decomposition to dual-pol data provided by Sentinel-1 covering different scenarios, such as agricultural, forest, urban and glacial land-ice. We show that the polarized term of received polarization state is not usually the same as the transmitted one, and can therefore be used for key applications, e.g., classification and geo-physical parameter estimation. We show that, for vegetated terrain, depolarization is not the only influencing factor to Sentinel-1 backscattered intensities and, in the case of vertical crops (e.g., rice), this allows the crop orientation effects to be decoupled from volume scattering in the canopy. We demonstrate that coherent dual-pol systems show strong phase signatures over glaciers, where the polarized contribution significantly affects the backscattered state, resulting in elliptical polarization on receive. This is a key result for Sentinel-1, for which dual-pol phase analysis coupled to dense time series offer great opportunities for land-ice monitoring.This work was funded by the Spanish Ministry of Science and Innovation, the State Agency of Research (AEI) and the European Funds for Regional Development (EFRD) under Projects TEC2017-85244-C2-1-P and PID2020-117303GB-C22, and by the University of Alicante under grant VIGROB-114

A new polarimetric change detector in radar imagery

In modern society, the anthropogenic influences on ecosystems are central points to understand the evolution of our planet. A polarimetric SAR (synthetic aperture radar) may have a significant contribution in tackling problems concerning land use change, since such data are available with any-weather conditions. Additionally, the discrimination capability can be enhanced by the polarimetric analysis. Recently, an algorithm able to identify targets scattering an electromagnetic wave with any degree of polarization has been developed, which makes use of a vector rearrangement of the elements of the coherency matrix. In the present work, this target detector is modified in order to perform change detection between two polarimetric acquisitions, for land use monitoring purposes. Regarding the selection of the detector parameters, a physical rationale is followed, developing a new parameterization of the algebraic space where the detector is defined. As it will be illustrated in the following, this space is 6 dimensional complex with restrictions due to the physical feasibility of the vectors. Specifically, a link between the detector parameters and the angle differences of the eigenvector model is obtained. Moreover, a dual polarimetric version of the change detector is developed, in case that quad-polarimetric data are not available. With the purpose of testing the methodology, a variety of datasets were exploited: quad-polarimetric airborne data at L-band (E-SAR), quad-polarimetric satellite data at C-band (Radarsat-2), and dual-polarimetric satellite data at X-band (TerraSAR-X). The algorithm results show agreement with the available information about land changes. Moreover, a comparison with a known change detector based on the maximum likelihood ratio is presented, providing improvements in some conditions. The two methodologies differ in the analysis of the total amplitude of the backscattering, where the proposed algorithm does not take this into consideration

Rice Phenology Monitoring by means of SAR Polarimetry at X-Band

The feasibility of retrieving the phenological stage of rice fields at a particular date by employing coherent copolar dual-pol X-band radar images acquired by the TerraSAR-X sensor has been investigated in this paper. A set of polarimetric observables that can be derived from this data type has been studied by using a time series of images gathered during the whole cultivation period of rice. Among the analyzed parameters, besides backscattering coefficients and ratios, we have observed clear signatures in the correlation (in magnitude and phase) between channels in both the linear and Pauli bases, as well as in parameters provided by target decomposition techniques, like entropy and alpha from the eigenvector decomposition. A new model-based decomposition providing estimates of a random volume component plus a polarized contribution has been proposed and employed in interpreting the radar response of rice. By exploiting the signatures of these observables in terms of the phenology of rice, a simple approach to estimate the phenological stage from a single pass has been devised. This approach has been tested with the available data acquired over a site in Spain, where rice is cultivated, ensuring ground is flooded for the whole cultivation cycle, and sowing is carried out by randomly spreading the seeds on the flooded ground. Results are in good agreement with the available ground measurements despite some limitations that exist due to the reduced swath coverage of the dual-pol HHVV mode and the high noise floor of the TerraSAR-X system.This work was supported by the Spanish Ministry of Science and Innovation (MICINN) and EU FEDER under Projects TEC2008-06764-C02-02 and TEC2011-28201-C02-02, by the National Program of Human Resources Movability under Grant PR2009-0364, by the University of Alicante under Project GRE08J01, and by Generalitat Valenciana under Projects GV/2009/079 and ACOMP/2010/082

Spaceborne Polarimetric SAR Interferometry: Performance Analysis and Mission Concepts

Spaceborne polarimetric SAR interferometry enables quantitative measurements of important bio- and geophysical parameters of the Earth surface on a global scale. We will first give a short review about actual and planned spaceborne SAR missions that can provide the observation space required for the derivation of Pol-InSAR products. This overview includes both repeat pass mission scenarios like ALOS/PalSAR, TerraSAR-L and Radarsat II, as well as single-pass mission scenarios like a fully-polarimetric Interferometric Cartwheel or TanDEM- X. The Pol-InSAR performance of the suggested mission scenarios will then be analysed by introducing the new concept of a phase tube. This concept enables an optimization of the system parameters and a quantitative comparison between different sensor configurations. The performance analysis for the investigated repeat pass mission scenarios reveals that major limitations have to be expected from temporal decorrelation. Some suggestions will be made to alleviate this performance loss by appropriate orbit refinement. Furthermore, important aspects in the design of future Pol-InSAR sensors will be addressed and we demonstrate the potential benefits arising from the use of bi- and multistatic single pass sensor configurations