ABSTRACT
Ambient occlusion (AO) is a shading technique that computes how much of the hemisphere around a surface point is blocked, and modulates the surface color accordingly. It is heavily used in production and real-time rendering, because it produces plausible global-illumination effects with relatively low computational cost. Recently it became feasible to compute AO in real time, mostly in the form of screen-space ambient occlusion (SSAO). SSAO techniques use the depth buffer as a discrete scene approximation, thus have a constant overhead and are simple to implement.
