Three dimensional interferometric synthetic aperture radar terrain

Abstract

Synthetic aperture radar data is used in conjunction with altimeter data to produce a terrain map corrected for platform roll angle. The technique uses two synthetic radar antennas and a ranging altimeter placed on an aircraft. The aircraft is moved in a set of substantially parallel flight paths where each flight is directly over the strip of terrain viewed by the synthetic aperture radar of an adjacent flight. During each flight the at least one antenna repeatedly transmits radar signals whose return echoes are received by both the first and second antennas. Conventional synthetic aperture radar processing yields a terrain map uncorrected for roll angle. The uncorrected terrain map data from one flight are compared with the altimeter data taken during an adjacent flight. This permits the altimeter data to be used to determine the roll angle when the corresponding synthetic radar data was taken. This roll angle measure is then used to correct the height and ground range of nearby points in the uncorrected terrain map. The result is a terrain map corrected for roll angle in a manner more accurate than can be obtained by direct measurement of the roll angle.