Hello, I am in process of finding the backscatter coefficients (sigma-nought) values for SAR acquisitions from ERS-1/2, Envisat, and PALSAR using the Geometric and Radiometric Calibration tool in SARscape. I have processed all of these datasets however the Envisat SAR data is the only dataset that has yielded reasonable results in dB. The others (ERS-1/2 and PALSAR datasets) give NaN values on output for the entire scene. For these satellites, I also checked some of the intermediate files (gamma-nought and beta-nought) and these also have NaN completely throughout the scene. Would anybody know what may be causing this to happen? I realize that there are a number of options in the geocoding default options. Would changing any of these settings likely fix this problem? Thanks again. Jon