ABSTRACT

This paper compares those synthetic aperture radar (SAR) parameters that are characteristic of airborne and orbital systems (e.g., SEASAT and SIR-A) by providing images of geologic significance for illustration. This comparison concludes that there is a major advantage of airborne SAR, specifically through its inherent flexibility in matching image acquisition flight paths and altitudes to enhance the geologic "grain" of the terrain and the prevalent relief

The latter factor is particularly significant in low relief areas such as the Texas Gulf Coast. Here, extensive SAR image coverage was acquired by flying the airborne system at a relatively low altitude, with the radar antenna tilted to a shallow angle. This combination of low altitude and antenna positioning provided a grazing illumination that highlighted, by shadowing, the otherwise subtle relief features in the resulting imagery.

The illumination-geometry-enhanced SAR imagery is utilized to discuss three case histories. Proceeding from east to west in the Gulf Coastal Plain of Texas these examples illustrate evaluations of an area of salt domes near Houston, an area of strong fractural control near Matagorda Bay, and an area of serpentine plugs near Luling and Austin.

Relative to the case history data presented, the paper includes a brief discussion of lineament analysis, emphasizing the nature and application in the subject interpretation situations.