Automated DEM extraction using RADARSAT ScanSAR stereo data

Terrain elevation extraction from stereo radar image pairs has been demonstrated to be a feasible technique for a variety of SARs. RADARSAT-1 has proven to be an especially flexible platform for collection of SAR imagery world-wide at a variety of resolutions and incidence angles. The authors demonstrate the utility of the ScanSAR beam mode for Digital Elevation Map (DEM) production with 50 m or better vertical accuracy. Extracting DEMs from RADARSAT ScanSAR data products offers the capability of providing topographic map data and orthorectified imagery for vast areas at an unprecedented low cost and quick response. Acquisition and processing of overlapping image products covering hundreds of thousands of square kilometers can occur within weeks regardless of cloud cover for almost any region of the Earth. This paper describes how, with proper processing techniques, a single ScanSAR image pair can be precisely coregistered to produce elevation models covering nearly 90000 square km at 150 m postings. Aspects of SAR processing and automated image matching critical to processing this beam mode are described. Orbital adjustment techniques utilizing little or no ground control are also discussed. Results from ScanSAR derived DEMs are contrasted with other SAR stereo beam combinations in terms of accuracy and suitability for various terrain types.