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.
This program was written by Scott Hensley, Paul Rosen, and Eric Gurrola of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Software category.
This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393-3425.
Refer to NPO-21205.
This Brief includes a Technical Support Package (TSP).
Software Processes SRTM ScanSAR Data Into Topographical Maps
(reference NPO-21205) is currently available for download from the TSP library.
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Overview
The document outlines a technical support package from NASA detailing a software program developed to process scan-mode synthetic-aperture radar (scanSAR) data into topographical maps, specifically during the Shuttle Radar Topography Mission (SRTM). The program was created by a team from the California Institute of Technology (Caltech) and NASA's Jet Propulsion Laboratory (JPL), consisting of Scott Hensley, Paul Rosen, and Eric Gurrola.
The software operates by first preprocessing the SAR data, which includes ancillary spacecraft motion, control, and calibration data. This preprocessing subdivides the data into latitude bands known as peg regions, formatting it for further processing. The main function of the processing subprogram is to generate strip maps from this preprocessed data using an algorithm adapted from airborne interferometric SAR mapping. This adaptation accommodates the burst mode of data collection used in the SRTM, where each burst typically consists of 50 to 80 radar pulses. This burst mode differs from traditional SAR strip mode, where every target is illuminated across the entire width of the radar beam.
The processing subprogram generates burst-level interferograms and combines them from multiple bursts to create accurate topographical maps. Initial results indicate that the program is functioning as intended, with expectations that it will produce the first globally consistent digital elevation map of the Earth.
The document also includes a notice that the software is available for commercial licensing, with contact information for Don Hart at Caltech for inquiries. It emphasizes that the work was conducted under the sponsorship of NASA and clarifies that the U.S. Government does not assume liability for the use of the information contained in the document.
Overall, this technical support package highlights a significant advancement in remote sensing and mapping technology, showcasing the collaboration between NASA and Caltech in producing a comprehensive digital elevation model that can enhance our understanding of Earth's topography. The program represents a crucial step in utilizing radar technology for global mapping efforts, with potential applications in various fields, including geography, environmental science, and urban planning.
