A computational approach to simulate subsurface light diffusion in arbitrarily shaped objects

Abstract

To faithfully display objects consisting of translucent materials such as milk, fruit, wax and marble, one needs to take into account subsurface scattering of light. Accurate renderings require expensive simulation of light transport. Alternatively, the widely-used fast dipole approximation [15] cannot deal with internal visibility issues, and has limited applicability (only homogeneous materials). We present a novel algorithm to plausibly reproduce subsurface scattering based on the diffusion approximation. This yields a relatively simple partial differential equation, which we propose to solve numerically using the multigrid method. The main dif culty in this approach consists of accurately representing interactions near the object's surface, for which we employ the embedded boundary discretization [5, 16]. Also, our method allows us to re ne the simulation hierarchically where needed in order to optimize performance and memory usage. The resulting approach is capable of rapidly and accurately computing subsurface scattering in polygonal meshes for both homogeneous and heterogeneous materials. The amount of time spent computing subsurface scattering in a complex object is generally a few minutes.