Implementation and experience of nationwide automatic satellite images registration system

A system for automatic ground control point measurement and rectification of satellite images to a nationwide reference database has been developed at VTT. The method is based on feature based matching. The reference database consists of about two hundred thousand features covering the whole Finland. The features are islands and lakes extracted from the nationwide Land Use Classification, produced from Landsat TM - images by the National Land Survey of Finland. Lakes and islands are extracted from the satellite image to be rectified. Their attributes are compared to those in the reference database. Using feature based matching and robust estimation a few hundred ground control points of subpixel accuracy are selected to the rectifi-cation. Images of different resolution can be measured automatically using this system. It has been tested with SPOT, Landsat TM and NOAA AVHRR imagery. The search for control points takes only a few minutes per satellite image. The accuracy of the result has proved to be at least as good as when measuring the control points manually. The method is analysed by the parallaxes between the reference features and the rectified images.