Global illumination

Global illumination algorithms used in 3D computer graphics are those which, when determining the light falling on a surface, take into account not only the light which has taken a path directly from a light source (direct illumination), but also light which has undergone reflection from other surfaces in the world (indirect illumination).

Images rendered using global illumination algorithms are often considered to be more photorealistic than images rendered using local illumination algorithms. However, they are also much slower and more computationally expensive to create as well. A common approach is to compute the global illumination of a scene and store that information with the geometry. That stored data can then be used to generate images from different viewpoints for generating walkthroughs of a scene.

Radiosity, ray tracing, beam tracing, cone tracing and photon mapping are examples of algorithms used in global illumination.

Also Monte Carlo or distributed ray tracing as well as variations like the metropolis light transport algorithm model diffuse inter-reflection which is a very important part of global illumination.

External links

• SplutterFish – developers of Brazil, a rendering system based on global illumination. The site has an extensive gallery of contributed images