The Loewner Order and Direction of Detected Change in Sentinel-1 and Radarsat-2 Data

When the covariance matrix formulation is used for multilook polarimetric synthetic aperture radar (SAR) data, the complex Wishart distribution can be used for change detection between acquisitions at two or more time points. Here, we are concerned with the analysis of change between two time points and the ``direction'' of change: Does the radar response increase, decrease, or does it change its structure/nature between the two time points? This is done by postprocessing/coprocessing the detected change with the Loewner order which calculates the definiteness of the difference of the covariance matrices at the two time points. We briefly describe the theory. Two case studies illustrate the technique on Sentinel-1 data covering the international Frankfurt Airport, Germany, and on Radarsat-2 data covering Bonn, Germany, and surroundings. We successfully demonstrate our ``direction'' of change approach to detected change areas.