Computing occlusion-free viewpoints

Methods for computing the locus of all viewpoints from which features on known polyhedral objects can be viewed in their entirety without being occluded by anything in the environment are presented. Convex and concave polyhedra with or without holes and the viewing model of perspective projection are used in this work. Based on properties of the occlusion-free and occluded loci of viewpoints, two methods for constructing these loci together with their complexity analysis are presented. In one method, a boundary representation of the occlusion-free locus is obtained. In the other, the locus of occluded viewpoints is expressed in terms of a constructive solid geometry representation that consists of a union of component solids. Implementation results are shown.