Three Dimensional Analysis Of Space Imageries

Abstract

Space imageries with their low costs and availability for every one, provide a good opportunity for topographic mapping of unmapped or poorly mapped areas around the world particularly in the developing countries. The French SPOT Imaging system is the first space orbiting satellite with stereoscopic capability. Panchromatic stereoscopic pairs with variable base to height ratios are available and can be arranged for any part on the earth's surface. In this investigation, three dimensional coordinates are extracted from SPOT stereoscopic images using two analytical photogrammetric methods. In the first method, a stereoscopic model is formed by using the analytical relative orientation technique. Three dimensional model coordinates, then, were fitted into ground coordinates using a number of mathematical models of coordinates transformation. The second method used is the space intersection, where three dimensional ground coordinates of the intersection point of each two similar rays are computed. This procedure, normally, follows the application of the space resection, where the exterior orientation elements for the two stereoscopic images have to be determined. To assess the accuracy of the extracted three dimensional coordinates, residuals and their root mean square values in a number of check points were computed and analyzed.