Jurassicprok is a computer program that generates strip-map digital elevation models and other data products from raw data acquired by an airborne synthetic-aperture radar (SAR) system. This software can process data from a variety of airborne SAR systems but is designed especially for the GeoSAR system, which is a dual-frequency (P- and X-band), single-pass interferometric SAR system for measuring elevation both at the bare ground surface and top of the vegetation canopy. Jurassicprok is a modified version of software developed previously for airborne-interferometric- SAR applications. The modifications were made to accommodate P-band interferometric processing, remove approximations that are not generally valid, and reduce processor-induced mapping errors to the centimeter level. Major additions and other improvements over the prior software include the following:
- A new, highly efficient multi-stagemodified wave-domain processing algorithm for accurately motion compensating ultra-wideband data;
- Adaptive regridding algorithms based on estimated noise and actual measured topography to reduce noise while maintaining spatial resolution;
- Exact expressions for height determination from interferogram data;
- Fully calibrated volumetric correlation data based on rigorous removal of geometric and signal-to-noise decorrelation terms;
- Strip range-Doppler image output in user-specified Doppler coordinates;
- An improved phase-unwrapping and absolute-phase-determination algorithm;
- A more flexible user interface with many additional processing options;
- Increased interferogram filtering options; and
- Ability to use disk space instead of random- access memory for some processing steps.
This program was written by Scott Hensley, Thierry Michel, Soren Madsen, Elaine Chapin, and Ernesto Rodriguez of Caltech for NASA’s Jet Propulsion Laboratory. This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393- 3425. Refer to NPO-40032.
This Brief includes a Technical Support Package (TSP).
Software for Generating Strip Maps From SAR Data
(reference NPO40032) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) detailing advancements in generating digital elevation maps (DEMs) using Synthetic Aperture Radar (SAR) technology. The focus is on the GeoSAR program, which aims to create wide-area DEMs beneath vegetation canopies at a reasonable cost, addressing challenges faced by traditional methods like photogrammetry and LIDAR.
GeoSAR employs a dual-frequency interferometric and polarimetric radar system operating in X and UHF bands, allowing simultaneous mapping on both sides of an aircraft. This innovative approach is designed to support high-fidelity DEM generation in a commercial production environment, with considerations for algorithm performance, throughput, maintainability, and extensibility.
The document outlines the technical processes involved in generating strip maps from raw radar data. Key components include motion compensation, which is crucial for achieving well-focused SAR imagery and accurate height maps. The processor incorporates two stages of motion compensation for both X-band and P-band data, ensuring that interferometric channels are co-registered and aligned. The data undergoes range compression, azimuth compression, and phase unwrapping to construct position vectors and generate height maps.
The software, referred to as jurassicprok, is designed to process both X-band and P-band data using tailored focusing algorithms to meet demanding decimeter-level height accuracy requirements. It includes features for estimating volumetric correlation, regridding height data into uniform grids, and propagating height error estimates. Various regridding algorithms are implemented, including nearest neighbor, simplical regridding, convolutional regridding, and surface fitting, each with its own advantages and considerations for noise reduction and spatial frequency preservation.
The document emphasizes the importance of generating bare surface elevation maps, which are essential for applications such as seismic hazard assessment and hydrology. It highlights the limitations of existing technologies and positions GeoSAR as a cost-effective alternative for mapping beneath dense vegetation.
Overall, the Technical Support Package showcases JPL's commitment to advancing radar technology for environmental monitoring and mapping, providing a robust framework for generating accurate and reliable elevation data essential for various scientific and commercial applications.
