Authors
Craig Donner, Henrik Wann Jensen
University of California, San Diego
Portals
Summary
This paper presented an efficient method for accurately rendering thin and multi-layered translucent materials based on a multipole diffusion approximation.
Abstract
This paper introduces a shading model for light diffusion in multi-layered translucent materials. Previous work on diffusion in translucent materials has assumed smooth semi-infinite homogeneous materials and solved for the scattering of light using a dipole diffusion approximation. This approximation breaks down in the case of thin translucent slabs and multi-layered materials. We present a new efficient technique based on multiple dipoles to account for diffusion in thin slabs. We enhance this multipole theory to account for mismatching indices of refraction at the top and bottom of of translucent slabs, and to model the effects of rough surfaces. To model multiple layers, we extend this single slab theory by convolving the diffusion profiles of the individual slabs. We account for multiple scattering between slabs by using a variant of Kubelka-Munk theory in frequency space. Our results demonstrate diffusion of light in thin slabs and multi-layered materials such as paint, paper, and human skin.
Contribution
- We present a multipole diffusion approximation for light scattering in thin slabs that uses an extension to diffusion theory based on the method of images
- We extend this multipole theory to account for both surface roughness and layers with varying indices of refraction, and we combine it with a novel frequency space application of Kubelka-Munk theory in order to simulate light diffusion in multi-layered translucent materials
- Our method generalizes to an arbitrary number of layers, and it enables the composition of arbitrary multi-layered materials with different optical parameters for each layer