The Isoluminance Contour Model

A standard method of simplifying the task of obtaining a shaded image of a solid object is to represent it by a collection of surface patches or a polyhedron. A smooth shading technique is then applied to each patch/facet to restore smoothness to the image. This paper introduces an entirely new approach to surface representation: the use of isoluminance contours to represent CSG-type primitive objects. The surface of an object is divided into strips by these contours, such that the area between two adjacent contours has a constant light intensity value. This method does not require any smooth shading technique and takes advantage of the polygon fill hardware facility available in many contemporary graphics devices. Ke ywords: computer graphics, isoluminance contours, constructive solid geometry, surface representation.