Screen space ambient occlusion (SSAO) is widely used in modern PC and console games to approximate global illumination effects. It gives good results when approximating occlusion in a uniform lighting environment, such as an outdoor scene on an overcast day.
Screen Space Directional Occlusion (SSDO) is a technique that was recently introduced to improve upon the visual quality of SSAO. It works by calculating occlusion and environmental lighting at the same time. However, due to
its significant computational cost, it is only practical to use SSDO with a small number of dynamic light sources or a global lighting environment stored in a cube map. The proposed algorithm allows dynamic light sources to take advantage of local occlusion information in a deferred shading pipeline, commonly found in modern games.