In computer graphics the global illumination rendering are a group of algorithms that provide solution, which add as realistic lighting as possible to 3 dimensional scenes. These algorithms produce more photorealistic pictures rather than algorithms using only local illumination. The Path tracing discussed in this thesis is one if the global illumination algorithms.
The Path tracing algorithm solves the illumination equation starting from the camera in the virtual space and heading backwards on the possible light routes to the light source. The quasi-Monte Carlo method used to the sampling of the light routes, and the importance sampling technique are used to improve the efficiency of the Path tracing. The materials of the objects, found in the virtual world, are defined with material models. These material models are the diffuse model, which describes matte surfaces, the specular model, which describes shiny surfaces, the ideal refractor, and the ideal reflector material models. Not only solid objects can be rendered by the Path tracing, inhomogeneous participating media can be rendered too. The light can go through this kind of media, but its material is heterogeneous, its density is varying.