Practical orthorectification of system corrected satellite images and its validation

Ortho-rectification of satellite imagery from original data was impossible for general users, but it is not so difficult from the system corrected data if we can obtain appropriate information about orbit trajectory on the earth. In this paper we derive the exact formulation of relief displacement due to surface elevation and propose a practical method for estimating the orbital trajectory and the scan direction from the image. The effectiveness of the method is verified using the RPC data as well as the orbit information attached to an ALOS PRISM image. The fine adjustment of scene center coordinates is performed by using a simulated shading image as reference at gridded areas, based on which geometrical accuracy of the corrected images are evaluated.