Practical Illumination from Flames
Ryusuke Villemin, Christophe Hery, Pixar Animation Studios · 2013
We present a method for creating and sampling volumetric light sources directly using the raw volumetric data under a Monte Carlo framework. Our algorithm does not require any preprocessing or baking, so it is compatible with progressive rendering. Since it does not use imposters, we can achieve high quality results with any mirror, glossy, or diffuse object. To be able to efficiently sample the volume emission, we use two strategies: light sampling (for the volume) and BRDF sampling (for the receiving object), and express them in the same domain so that we can apply multiple importance sampling (MIS) to compute the final result. Our technique focuses on the emission portion of volumetric rendering and is complementary to all other recent publications handling scattering effects.