Radiometric calibration by natural targets: methods and performance evaluation

PS-cal traditionally exploits the amplitude of stable targets to calibrate data stacks. Here we show that such approach suffers of a non-stationary biasing due to fluctuations in SCR that may lead to a significant performance loss. We discuss a coherent based, bias-free estimator. The method exploits much more PS than the non-coherent case, thus it can be applied to small image blocks, to detect local artifacts, and it is robust when few images are given. Comparative analysis of the two approaches and results based on COSMO SKYMED data are shown.