Evaluation of terrain models for the geocoding and terrain correction of synthetic aperture radar (SAR) images

Synthetic aperture radars (SAR's) are well suited for the measurement of geophysical parameters but the application of SAR imagery is limited by geometric and radiometric effects caused by variable terrain. Terrain models may be used for the rectification of SAR images, but model quality limits the extent of error correction. Various terrain models (USGS, SPOT, and 1 deg models) were used to rectify a Seasat SAR image in order to quantify terrain model differences and their effects on SAR image terrain correction. The accuracy of geocoded and terrain-corrected images was assessed, terrain models were compared, and the effects of terrain model differences on corrected SAR images were analyzed. Results indicate that elevation errors in terrain models are amplified into location errors in the terrain-corrected images. USGS and SPOT terrain-corrected images are superior to the image corrected by the 1 deg terrain model or geocoding using a constant elevation.