AUTOMATED DEM EXTRACTION AND ORTHOIMAGE GENERATION FROM SPOT LEVEL 1BIMAGERY

This paper describes the testing and validation of the photogrammetric modules of the PCI EASI/PACE system using SPOT stereo-pairs over a hi gh accuracy test field established in a desert area in Jordan. The mat hematical modeling and analytical photogrammetric solution used by the system are first described. This is followed by a description of the algorithm employed in the automatic image matching procedure used to e xtract a dense DEM from the SPOT digital image data. The results of ex tensive tests of the geometric accuracy of the exterior orientation an d analytical rectification carried out with the SPOT images using EASI /PACE are given. The DEMs generated from five SPOT Level 1B stereo-pai rs have been merged and validated through a comparison of the resultin g contours with the corresponding contours generated by aerial photogr ammetric methods, the two plots showing an excellent agreement. The fi nal ortho-images are of a high quality in radiometric terms, while a c heck of their geometric accuracy reveals sub-pixel accuracy. The resul ts of this highly automated all-digital photogrammetric procedure are of considerable relevance to those concerned with the topographic mapp ing of extensive areas of arid and semi-arid terrain.