Raytracing

(Term of computer graphics)

A method of computer graphics, normal used to create synthetic images of imaginary scenes in space.

There are two variants of raytracing:

Forward Raytracing
In this case, the program simulates rays of light (or other spectra) that emanate from a light source, and determines where they end up when following a number of reflecion on scene surfaces. This method is normally used in the design of luminaire reflectors and other optical equipment.

Backwards Raytracing
Here the program starts with scene, and casts rays into different directions, until they hit a surface in the scene. At this point, it tries to find out what amount of light is available to illuminate this surface. This can happen with the help of an ambient term, which represents an (unrealistic) global brightness of the scene, by determining the distance to one or several light sources, or recursively by sending more rays into the scene from that point on. A combination of the last two methods, called distributed raytracing, is the most interesting one for our purposes.

Distributed Raytracing
Stochastic Raytracing
This is a very powerful approach for simulating the diffuse light distribution and reflection in three dimensional environments (the "global illumination model") and is used in the Radiance software.

Distributed raytracing can simulate scenes of extreme complexity quite effectively, while for scenes with very high numbers of light sources the radiosity approach often has some advantages.