Design and Implementation of Parallel XDraw Algorithm Based on Triangle Region Division

Terrain viewshed analysis is the basis of studying on the terrain applications such as observation point siting and shortest path planning. With the rapid development of digital photogrammetry and remote sensing, at the time of getting large scale terrain data, it also puts forward higher requirements for the efficiency and method of the viewshed calculation. In this paper, a parallel XDraw viewshed analysis algorithm is proposed on the process and level. The algorithm presents a fine-grained data scheduling strategy between different layers. Firstly, it divides DEM terrain data into a lot of triangular regions. Then, the algorithm schedules the data with a triangular region in row or column as a thread and calculates the visibility of each grid unit on a row or column. Experimental results show that the proposed method can greatly improve the computational efficiency comparing with other existing methods.