Volumetric lighting

Volumetric lighting, also known as "God rays", is a technique used in 3D computer graphics to add lighting effects to a rendered scene. It allows the viewer to see beams of light shining across the environment. Examples of volumetric lighting are seeing sunbeams shining through a window and seeing sunbeams radiating when the Sun is below the horizon, also known as crepuscular rays. The term seems to have been introduced from cinematography and is now widely applied to 3D modeling and rendering, especially in the development of 3D video games.

In volumetric lighting, the light cone emitted by a light source is modeled as a transparent object and considered as a container of a "volume". As a result, light has the capability to give the effect of passing through an actual three-dimensional aerosol (e.g. fog, dust, smoke, or steam) that is inside its volume, just like in the real world.