Generation of Fine Resolution DEM at Test Areas in Alaska Using ERS SAR Tandem Pairs and Precise Orbital Data

The ASF Science division has released the world's first free end-to-end interferometric digital elevation model (DEM) generation system. This software, which processes from raw signal data through to a map-projected, ground-range 20m DEM, is completely automated. Preliminary comparison with differential gobal positioning system (GPS) indicates that over a 100km swath, horizontal position errors are less than 120m, and comparison with the 2x3 arc second United States Geological Survey (USGS) DEM indicates an average vertical error of 7m, 25m RMS. This result was obtained from an ERS tandem pair over Delta Junction, Alaska. These advances in accuracy are due to use of precision timing and orbital data in an interferometric SAR processor using an average doppler, precise baseline refinement, and direct ground rectification. The computationally intensive nature of these algorithms was minimized through the creation of a parallel SAR processor and a linearized ground rectification procedure.