Unstructured versus structured GLRT for multi-polarization SAR change detection

Coherent multi-polarization SAR change detection exploiting data collected from N multiple polarimetric channels, is addressed in this paper. The problem is formulated as a binary hypothesis testing problem and a special block-diagonal structure for the polarimetric covariance matrix is forced to design a detector based on the Generalized Likelihood Ratio Test (GLRT) criterion. It is shown that the structured decision rule ensures the Constant False Alarm Rate (CFAR) property with respect to the unknown disturbance covariance. Results on both simulated and real high resolution SAR data show the effectiveness of the considered decision rule and its superiority against the traditional unstructured GLRT in some scenarios of practical interest.