This paper describes an experiment for a proposed scheme using onboard satellite data to perform three-dimensional positioning for a pair of SPOT stereostrips. Based on the sampling geometry of French SPOT satellite images, we first adjusted the on-board parameters by incorporating a small number of ground control points (GCPs). Then a procedure for three-dimensional modeling was performed as follows. The central features of the proposed scheme are: (1) use of onboard data to initialize orbit parameters and attitude data for the satellite; (2) correction of on-board parameters with low order polynomials; (3) use of reverse transformation to check the collinear relationship between object space and image space for the GCPs; (4) adjustment of attitude data for the satellite to minimize the error in terms of the GCP collinearity; and (5) space intersection. Experimental results indicate that, for a SPOT panchromatic stereostrip with a 0.6 base-to-height ratio and a 45 km by 280 lan stereo model area, the root-mean-square-error for 3-D positioning is less than 8 m in each direction when only 4 GCPs are used.
