Adaptive Ray Tracing of Subdivision Surfaces

Subdivision Surfaces as well as (interactive) ray tracing have become an important issue in computer graphics. But ray tracing of subdivision surfaces has received only little attention. We present a new approach for ray tracing of subdivision surfaces. The algorithm uses a projection of the ray onto the surface and works mainly in two dimensions along this projection. While proceeding from patch to patch, we examine the bounding volume of their borders: the lower the distance between ray and subdivision surface, the more refinement steps are adaptively applied to the surface but only along the projection of the ray. The adaptive refinement of a patch is controlled by curvature, size, its membership to the silhouette, and its potential contribution to the light transport. The algorithm is simple and mainly consists of elementary geometric computations. Hence it is fast and easy to implement without the need for elaborate preprocessing. The algorithm is robust in the sense that it deals with all features of subdivision surfaces like creases and corners.