The invention discloses an SAR
geometric distortion identification method based on a local incidence angle and virtual topographic change, and the method comprises the steps: extracting a
radar incidence angle and a
satellite azimuth angle according to the SAR data of a target region, and calculating a
radar sight line
azimuth angle; dEM data of a target area are acquired, a
slope angle and a slope direction are calculated, and a
radar incident angle and a radar
sight line
azimuth angle are spatially interpolated into a DEM grid; calculating a local incident angle according to a radar incident angle, a radar
sight azimuth angle, a
slope angle and a slope direction in the DEM grid; determining four types of active
geometric distortion information including perspective contraction, active
overlay, resolution enhancement and active shadow according to the relation between the local incident angle and the radar incident angle; a critical point of the active
geometric distortion area is searched, a virtual
terrain is constructed pixel by pixel, a
slope angle of the virtual
terrain is calculated, and a position, equal to an incident slope angle, of the slope angle of the virtual
terrain is searched through changes of the slope angle of the virtual terrain, so that a passive geometric
distortion area is determined; and superposing the active geometric
distortion and the passive geometric
distortion to obtain final geometric distortion.