Radiometric corrections and calibration of SAR images

Specific characteristics of SAR images are the result of the imaging radar technique, which produces radiometric and geometric distortions. The main radiometric distortions are due to the spreading loss effect, the non-uniform antenna pattern, possible gain changes, saturation and speckle noise. The main geometric distortions are projection in slant range, foreshortening, layover and shadowing. To remove or reduce the distortions arising from these effects the application of image preprocessing procedures is necessary. This paper presents the procedures for preprocessing ERS/SAR and Radarsat images in terms of the radiometric corrections and calibration. Procedures for estimating the input filtering parameters for speckle reduction are also presented