Editing Global illumination (section)

==Algorithms==
Images rendered using global illumination algorithms often appear more [[Photorealism|photorealistic]] than those using only direct illumination algorithms. However, such images are computationally more expensive and consequently much slower to generate. One common approach is to compute the global illumination of a scene and store that information with the geometry (e.g., radiosity). The stored data can then be used to generate images from different viewpoints for generating walkthroughs of a scene without having to go through expensive lighting calculations repeatedly.

[[Radiosity (computer graphics)|Radiosity]], [[Ray tracing (graphics)|ray tracing]], [[beam tracing]], [[cone tracing]], [[path tracing]], [[volumetric path tracing]], [[Metropolis light transport]], [[ambient occlusion]], [[photon mapping]], [[Signed_distance_function|signed distance field]] and [[image-based lighting]] are all examples of algorithms used in global illumination, some of which may be used together to yield results that are not fast, but accurate.

These algorithms model [[diffuse inter-reflection]] which is a very important part of global illumination; however most of these (excluding radiosity) also model [[specular reflection]], which makes them more accurate algorithms to solve the lighting equation and provide a more realistically illuminated scene.  The algorithms used to calculate the distribution of light energy between surfaces of a scene are closely related to [[heat transfer]] simulations performed using [[Finite element analysis|finite-element]] methods in engineering design.