Abstract

We present an extension of irradiance caching [Ward88] to participating media. Our method is based on Monte Carlo ray tracing, and it exploits the smooth nature of scattering in participating media by caching radiance accurately at a sparse set of locations and using interpolation to evaluate the radiance at arbitrary points in the medium. We compute gradients of the radiative transport equation to estimate the local variation of the scattered radiance and to improve the accuracy of interpolation. Our approach handles both heterogeneous media and anisotropic phase functions, and it is several orders of magnitude faster than path tracing. Furthermore, it is view driven and well suited in large scenes where methods such as photon mapping [Jensen98] become costly (see Figure a, b and d).

Reference: Wojciech Jarosz, Craig Donner, Matthias Zwicker, and Henrik Wann Jensen "Radiance Caching for Participating Media" SIGGRAPH 2007, Technical Sketch

Radiance caching for participating media [3MB pdf]