A Fast Approach to Detect Occlusions for Large-scale True Orthophoto Generation

Abstract:

Previous efforts did not provide an accurate and fast way for generating true othorphoto. This paper tries to solve the problem by analyzing the complexity of algorithm processes and finding the optimum manner to allocate them. In this paper, an optimum segmentation number (OSN) for radial sweep is presented to achieve minimum complexity. First, the scan area, number of azimuth lines and visibility judgment area of radial sweep and spiral sweep method have been discussed with rigorous geometric theory, and then the algorithm complexity of both methods are estimated with mathematical computation theory. At last, minimum complexity of methods is obtained based on extreme point theory of differential calculus. Experiments have demonstrated that the proposed method has the best efficiency, and is efficient to avoid “M-potion” problem, and false occlusions and false visibilities caused by the rolling area, the incompatibility between the DSM and ground image resolution. The deduction and experiments indicate that the proposed method is a robust, accurate, fast and effective approach to generate high quality true orthophoto at a large scale.