Software Processes SRTM ScanSAR Data Into Topographical Maps

A computer program automatically generates topographical maps from data collected by scan-mode synthetic-aperture radar (scanSAR) during the Shuttle Radar Topography Mission (SRTM). A preprocessing subprogram subdivides the SAR data, along with ancillary spacecraft-motion, control, and calibration data, into latitude bands called peg regions and puts out the data in a coordinate system and format appropriate for a processing subprogram. The main function of the processing subprogram is to generate strip maps from the preprocessed data, by use of an algorithm developed previously for airborne interferometric SAR mapping and modified to accommodate the burst mode of collection of SAR data of the SRTM (each burst normally comprising between 50 and 80 pulses). The SAR burst mode stands in contrast to the traditional SAR strip mode, in which every target is illuminated for the entire along-track width of the radar beam. The processing subprogram generates burst-level interferograms, then combines interferograms from multiple bursts in such a way as to generate accurate topographical maps. Results of processing thus far indicate that the program is working as intended and confirm the expectation that the program will generate the first globally consistent digital elevation map of the Earth.