A NOVEL VISIBILITY DETERMINATION ALGORITHM BASED ON POLAR COORDINATES

Visibility determination algorithms aim to eliminate the time wasted in rendering invisible objects in order to speed up the rendering process. Only visible objects from the current viewer position are sent to the rendering phase. In this paper a new exact visibility determination method based on using the polar coordinates of the vertices of a scene s objects is proposed. In the preprocessing stage four sorted lists of the objects are constructed. At running time one or more of these lists are used to determine the visible objects from the current viewer position. The proposed algorithm runs in O(mn) time, where m is the number of objects in the whole scene and n is the number of visible objects from the current viewpoint. Satisfying experimental results have been obtained for both 2D and 2.5D scenes