High-Precision Direct Geolocation Based on Estimation of View Vector Error

Through the example of SPOT satellites, this paper analyzes the relationship between the view vector error and the error of direct geolocation. A precise estimation formula for view vector error is derived theoretically. Based on this formula, a high-precision direct geolocation method is proposed, together with an exact, step-by-step procedure. With only a few ground control points (GCPs), this method can estimate precisely the view vector error, achieving the purpose of precise, zero-control-point geolocation of other scenes of the same orbit in a certain time interval. The results of experiments and comparative analysis show that this method is an effective, high-precision direct geolocation method with sparse GCPs.