Ray Casting on the GPU

Abstract

In Chapter 1 we introduced the global illumination problem as the solution of the rendering equation. To evaluate the integral numerically, we need samples, and those samples are light paths. In one way or another, all algorithms have to generate light paths connecting the lights with the camera. The most straightforward and general approach is to use ray casting, which intersects scene surfaces with a half-line called the ray and returns the intersection that is closest to the start of the ray. Classic and successful global illumination methods such as path tracing [72], photon mapping [69, 68, 70], or virtual light sources [78] rely on this operation.