Ray Tracing of Subdivision Surfaces

Abstract

We present the necessary theory for the integration of subdivisionsurfaces into general purpose rendering systems. The most importantfunctionality that has to be provided via an abstract geometry interfaceare the computation of surface points and normals as well as theray intersection test. We demonstrate how to derive the correspondingformulas and how to construct tight bounding volumes for subdivisionsurfaces. We introduce envelope meshes which have the same topologyas the control meshes but tightly circumscribe the limit surface.An efficient and simple algorithm is presented to trace a ray recursivelythrough the forest of triangles emerging from adaptive refinementof an envelope mesh.