The exact solution of the imaging equations for crosstrack interferometers

The focus of this paper is on deriving the exact solution of the two sets of Interferometric Range-Doppler Equations for airborne and spaceborne crosstrack interferometers. Due to the generality of the presented problem the obtained solution process is also valid for Stereo-SAR applications. Selecting a special moving coordinate system the equations simplify sufficiently to result in a very efficient algorithm which offers several advantages over existing phase-to-height transformations: The influence of relevant parameter errors on DTM deformation can be studied, nonstandard imaging geometries are properly described, part of the solution is given in an analytic form which considerably increases processing speed and precision, the DTM is obtained with its natural earth curvature thus no additional ellipsoidal model is required. It is shown that phase calibration with ground control coordinates in the presence of parameter errors invariably leads to a tilted DTM and that the DTM deformation cannot be traced back to particular errors which means their separation is not possible.