Geometric Correction of Pushbroom-type High Resolution Satellite Images

This paper describes a geometric correction algorithm for high-resolution pushbroom type sensor images. In the systematic correction module, a sensor-orbit-Earth model was designed by using a vector projection technique which resulted in a forward transformation from raw image coordinates to geocentric coordinates . In order to avoid a large amount of computational load of the forward transformation algorithm, an inverse transformation algorithm was derived: The inverse transformation algorithm reduces the processing time significantly in resampling process. A precision geometric correction algorithm was also developed. Ground Control Points (GCPs) were extracted from scanned map images instead of paper maps attached on a digitizing table. The use of scanned raster map images for the GCP extraction gave many advantages for an operator as well as good accuracy. The GCPs extracted from a raw image and a scanned map image were used to estimate the values of geometric error sources such as the position, velocity and attitude of the satellite. An extended Kalman filter was used for the optimal estimation. The geometric correction algorithm described in this paper was included in a pre-processing software for the KITSAT-3 highresolution multi-spectral sensor images. The pre-processing software was developed by using Visual C++ programming language and it will run on PC-WindowsTM environment.