Abstract:

As a kind of spatial analysis method of 3DGIS, viewshed analysis has a wide application in urban planning,military and archaeology. And its realization is mainly based on visibility analysis. In this paper, the minimum rectangle bounding box of one building is extracted based on the relative regularity of the shape of three-dimensional models of most urban buildings. Based on the position of the viewpoint and the building models, the visible points of each building model are extracted.Then we connect the viewpoint and the visible points of the building model in turn to generate a cone.We make the difference set between the projection area on the plane of one cone bottom surface and the polygon of the other one cone bottom surface as the visible surface of one building model, thus avoiding calculating the visibility of every point of the building model and reducing the computation amount.The final visualization of the results also proves the feasibility and effectiveness of the algorithm.

Key words: 3D city, viewshed analysis, 3DGIS