Method for orthocorrecting satellite-acquired image

Abstract

A method is provided for the orthocorrection of a satellite-acquired image. This method can be applied even if ground control points are not set. Without propagation of an error throughout the image and also without needing an excessively large amount of calculations, the method makes it possible to correct ground-relief-associated distortions caused by the relief of a ground surface. According to the method, a plurality of control planes of different elevations are set relative to a control plane of a zero elevation of a reference rotating ellipsoidal earth model. A corrected image is divided into blocks by lattices of equal intervals. With respect to each of these blocks, distortion model formulas in the form of bilinear functions are determined for the respective control planes. Concerning each pixel position in the corrected image, two pixel positions in an observed image, which correspond to the elevation value of the pixel position in the block, are calculated by using distortion model formulas for two control planes which directly sandwich the value of elevation above and below the value in the corresponding block. By the value of elevation, the two pixel positions are linearly interpolated to determine the desired pixel position in the observed image.