Fundamentals of Computer Graphics, 4th Edition

Chapter 23

Global Illumination

Many surfaces in the real world receive most or all of their incident light from other reflective surfaces. This is often called indirect lighting or mutual illumination. For example, the ceilings of most rooms receive little or no illumination directly from luminaires (light-emitting objects). The direct and indirect components of illumination are shown in Figure 23.1.

Although accounting for the interreflection of light between surfaces is straightforward, it is potentially costly because all surfaces may reflect any given surface, resulting in as many as O(N2) interactions for N surfaces. Because the entire global database of objects may illuminate any given object, accounting for indirect illumination is often ...