Abstract

Steve Marschner: Volumetric light transport in realistic rendering

From the viewpoint of physics, realistic rendering is all about solving for the distribution of light energy in a scene, a problem known as light transport.  There are two versions of this problem used in rendering: surface light transport, in which light reflects from surface to surface with nothing in between, and volume light transport, in which light interacts continuously with the medium it's passing through.  Traditionally most rendering uses surface light transport, with volumetric methods reserved for effects like fog, smoke, clouds, etc.

More recently, volumetric light transport has been used as a model for what happens inside a material, leading to important advances in rendering translucent materials like skin.  It can also be used to produce the correct appearance for "materials" that are made up of macroscopic parts but behave translucently on a large scale.  We are working on applications of volumetric methods to materials like this, which aren't really continuous media but can sometimes be treated as such, with realistic rendering of human hair as the motivating example.

In this talk I'll present the basics of volume light transport (also known as radiative transfer) and talk about its graphics applications in the context of my broader research in simulating materials for realistic rendering.