GEOMETRIC CORRECTION OF REMOTE SENSING SATELLITE DIGITAL IMAGES USING MAPPING POLYNOMIAL OF DIFFERENT ORDERS

Abstract

All remote sensing imagery, from satellites, is inherently subjected to geometric distortions. Therefore geometric corrections, as preprocessing operations, are normally required prior to imagery analysis and extraction of information. This paper conducts geometric correction procedure of sample of raw satellite images using georeferenced images (image-to-image registration) of the same area. In this procedure, many well-distributed ground control points (GCPs) pairs (from both images) are identified. Then a proper transformation polynomial is applied to map the original image GCPs coordinates into the new georeferenced image GCPs coordinates. A resampling process is carried out to recalculate the gray level values for pixels in the transformed output image (new pixels locations) based on pixel values in the input image. Also, this paper presents an analysis study of the effect of variation of the number of GCPs and the order of the mapping polynomials on the accuracy of geometric correction process. The Root Mean Square Error (RMS), at the selected GCPs, are calculated and used as a measure of accuracy of the obtained results.