Determining the coherence matrix for single look polarimetric SAR data

Abstract

The coherence matrix from the scattering matrix of a single look polarimetric SAR pixel will have an entropy of zero with the main eigenvalue being equal to the span and the other two eigenvalues being equal to zero. Each scattering matrix element from terrain scatter is a coherent sum from a large number of scatterers in a resolution cell. Entropy/alpha decomposition is only possible where the coherency matrix elements are determined from ensemble covariances. This is the case for multilook polarimetric SAR data where covariances from the exact same collection of scatterers are averaged using separate extraction filters in the SAR doppler direction. We report interesting observations from analysis of multilook SIR-C data at L and C bands from different oceans around the globe. We present a strategy for segmenting single look polarimetric TerraSAR ocean data using an algorithm we have previously developed with the averaging of the resulting like pixels used to generate coherence matrices. We give a brief discussion of desert surfaces.