Images rendered using global illumination algorithms are often considered to be more photorealistic than images rendered using 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, and [photon mapping]? are examples of global illumination algorithms.