Effect of Ground Control points Location and Distribution on Geometric Correction Accuracy of Remote Sensing Satellite Images

The most common approach for geometric correction is the use of mapping polynomial. . It depends on selection of several clearly discernible points, called ground control points (GCPs), in the distorted image, and map them either to their true positions in ground coordinates (e.g. latitude, longitude) measured from a map, or to georeferenced image (corrected before), coordinates of corresponding points, through a mathematical transformation, that will convert the raw image coordinates into the desired coordinates. The accuracy of the geometric correction process depends mainly on the number of selected GCPs (polynomial order), the identified features on the image (road intersections, airport runway intersections, bends in rivers features and the like), and on the distribution of the selected GCPs over the distorted image area.