Ambient occlusion is a shadowing technique used in graphics to make 3D objects look more realistic by simulating the soft shadows that should naturally occur when indirect or ambient lighting is cast out onto a scene. It is a method to approximate how bright light should be shining on any specific part of a surface, based on the light and its environment, and is used to add realism. Ambient occlusion shading is actually fake indirect shadows that are added into the render by rays that get cast out from each surface on the geometry. If these rays come into contact with another surface, that area will become darker. If they don’t find another surface, the area will stay brighter. These soft ambient occlusion shadows help to define and separate the objects in a scene and add another level of realism to the render.

Ambient occlusion is great for softening the overall lighting in a scene if it’s too bright. There is no need to add additional lights because ambient occlusion does not work in the same way as “final gather” which must use a light source to cast out rays. Ambient occlusion is also great for visualizing a model that hasn’t even been textured yet. It is a subtle, yet effective way of really making a level or scene come to life and seem more realistic.

Ambient occlusion can be enabled in games through the graphics settings. There are different types of ambient occlusion, such as screen space ambient occlusion (SSAO), horizon-based ambient occlusion (HBAO), and voxel ambient occlusion (VXAO) . However, enabling ambient occlusion can have an impact on performance, and the difference between different types of ambient occlusion can be subtle.