A program for direct georeferencing of airborne and spaceborne line scanner images

Abstract

For high quality direct georeferencing it is important that all geometric parameters influencing the rectification process are taken into account. These parameters are the exterior and interior orientation of the imaging system, the digital terrain model, the boresight misalignment and the mapping coordinate reference system. For airborne scanner images covering an area of only some miles extension simplifying assumptions can be made without noticeable loss of accuracy; e.g. the position and attitude data can be directly related to the geographic reference system. In airborne applications a high precision navigation sensor system (IMU, DGPS) aligned to the scanner system was used to obtain the parameters of the exterior orientation. Orthoimages were generated with 1-2 pixel accuracy from pushbroom and whiskbroom scanner images. To rectify space imagery it is necessary to use orthogonal coordinate systems (e.g. Local Topocentric Systems) in an intermediate processing step before finally the result are transformed to a map projection system. Orthoimages were produced from images of the German space camera MOMS-2P. The software package RECTIFY was developed by DLR and serves as a generic geometry processor for data of different sensor types and navigation systems. It supports all well known coordinate- and map projection systems as well as different geodetic datums. Methods and theory underlying the software package and application examples of airborne and spaceborne imagery will be presented.