COMPUTING OCCLUSION-FREE VIEWPOINTS

This paper presents methods to compute the locus of all viewpoints fro m which features on known polyhedral objects can be viewed in their en tirety without being occluded by anything in the environment. Convex a nd concave polyhedra with or without holes and the viewing model of pe rspective projection. are employed in this work. Initially, properties of the occlusion-free and occluded loci of viewpoints are determined. Based on these properties, two methods to construct these loci togeth er with their complexity analysis are presented. In the first method, a boundary representation of the occlusion-free locus is obtained. In the second method, the locus of occluded viewpoints is expressed in te rms of a constructive solid geometry (CSG) representation that consist s of a union of component solids. Implementation results and compariso n of the two methods are given.