Computing non-visibility of convex polygonal facets on the surface of a polyhedral CAD model

Visibility has found wide applications in manufacturing operations planning and computer vision and graphics. The motivation of this paper is to accurately calculate visibility for objects whose surface is represented by polygonal facets. In this paper, the authors focus on determining non-visibility cones, which are the complementary sets of visibility. This is accomplished by determining sliding planes that comprise the boundaries of a non-visibility cone. The approach presented in this paper directly evaluates the boundaries of the non-visibility cone of an arbitrary convex planar polygon due to the visibility blocked by obstacle polygons. The method is capable of calculating visibility for convex polygons with any number of sides, not limited to triangular facetted models. Implementation is demonstrated in this paper for three to six sided polygonal models. (C) 2007 Elsevier Ltd. All rights reserved.