Geometric positioning of multi-source optical satellite imagery for the island and reef area with sparse ground control points

The optical satellite imagery with high resolution and large coverage has been widely applied to gain the geospatial information of island and reef area. In this paper, according to the repeated observation of satellites, the method of georeferencing with multi-source optical satellite imagery is presented, in which the constraint model is introduced in to solve the rank defect of the coefficient matrix of normal equation. Results from combined block adjustment indicate that the test with more images from different directions performs best. The conclusion is drawn that multi-source images can increase not only the redundant observation, but also the base-height ratio, which can improve the positioning accuracy, providing a way to the island and reef mapping without GCPs. Then the absolute position of the images can be obtained with sparse GCPs.