ABSTRACT
Illumination or lighting refers to the techniques handling the interaction between light sources and objects. The lighting models are often divided into two categories: local illumination and global illumination. In general, the local illumination model considers only direct lighting . The illumination of a surface depends solely on the properties of the surface and the light sources. In the real world, however, every surface receives light indirectly . Even though light sources are invisible from a particular point of the scene, light can be transferred to the point through reflections or refractions from other surfaces of the scene. The global illumination model considers the scene objects as potential indirect light sources.
