Satellite Image Orientation

The number of high and very high resolution optical satellites, as well as the number of medium resolution small satellites is growing permanently. With the ground sampling distance (GSD) of 0.5m available now, a competition to aerial photographs down to the image scale 1 : 20 000 exists. The satellite image orientation is depending upon the image product. Mainly close to original images, traditionally named level 1A, and images projected to a plane with constant height, traditionally named level 1B, are available. The satellite image orientation may be based on a reconstruction of the image geometry, supported by some approximate orientation information in the image header file, or the orientation information distributed together with the image as rational polynomial coefficients can be used in a bias corrected manner. Another possibility are general approximate orientations like 3Daffine transformation, DLT or the generation of a reduced number of RPC-elements based on ground control points (GCP). The methods are analyzed and compared by means of different satellite image types.