A Four–Component Decomposition of POLSAR Images Based on the Coherency Matrix

Abstract—A four-component scattering model is proposed to decompose polarimetric synthetic aperture radar images. The covariance matrix approach is used to deal with the non-reflection symmetric scattering case. This scheme includes and extends the three-component decomposition method dealing with the reflection symmetry condition that the co-pol and the cross-pol correlations are close to zero. Circular polarization power is added as the fourth component to the three component scattering model which describes surface, double bounce, and volume scattering. This circular polarization term is added to take account of the co-pol and the cross-pol correlations which generally appear in complex urban area scatttering and disappear for natural distributed scatterer. Keywords-radar polarimetry; target decomposition; covariance matrix; non-reflection symmetry; POLSAR I