An Incoherent Decomposition Algorithm Based on Polarimetric Symmetry for Multilook Polarimetric SAR Data

Polarimetric symmetry, including reflection symmetry, rotation symmetry, and azimuthal symmetry, are useful concepts for describing the scattering characteristics of polarimetric synthetic aperture radar (SAR) data. In this study, for the coherency matrices of multilook polarimetric SAR data, three new scattering models were first proposed based on the polarimetric symmetry. Then, a four-component incoherent decomposition algorithm was introduced, which was based on the three aforementioned new models, along with a classic volume scattering model. The proposed algorithm was considered to be a complete incoherent decomposition algorithm. No polarimetric information was lost during the decomposition. Also, there were no negative powers in its output. Then, by utilizing three polarimetric SAR images which had been derived by ESAR, RADARSAT-2, and GF-3, respectively, the experimental results had revealed that the proposed decomposition algorithm was effective in the analysis of the scattering mechanisms of terrain targets. It was observed that more than 90% of the coherency matrices of the real polarimetric SAR data had been completely decomposed by the proposed algorithm into four components. These components were found to be exactly consistent with the scattering models for surface scattering, double-bounce scattering, volume scattering, and helix scattering. The proposed decomposition algorithm had provided insight into the limitations of incoherent decomposition.