Wide-area terrain surveying with interferometric SAR

For many applications, extraction of useful data from synthetic aperture radar (SAR) or other sensor imagery of the Earthʹs surface can be expedited by encoding terrain relief cues within the image. Shadowing may provide qualitative cues, but the most accurate relief information results from direct measurement of terrain elevation on a pixel-by-pixel basis. Airborne interferometric SAR (IFSAR) offers a method for the generation of digital elevation maps (DEMs) which has recently come of age technologically. Before semiautomated IFSARE (IFSAR elevation) mapping becomes commercially practical, concerns in the areas of accuracy, reproducibility, throughput, and cost must be addressed. This article considers these issues in the context of a study which was conducted with a production military SAR system flown in an experimental IFSARE mode. Example IFSARE imagery from an associated Army /ARPA mapping program is presented and analyzed for detail. Geopositioning accuracy and reproducibility are discussed, one standard was a set of high accuracy, high resolution DEMs which were produced from optical photo stereo pairs and controlled by a GPS-based ground survey. Computer throughput requirements are assessed from the standpoint of near real-time processing and low cost.