Distance fog is a technique used in 3D computer graphics to enhance the perception of distance by simulating fog. Because many of the shapes in graphical environments are relatively simple, and complex shadows are difficult to render, many graphics engines employ a "fog" gradient so objects further from the camera are progressively more obscured by haze. This technique works because of light scattering, which causes more distant objects to appear hazier to the eye, especially in outdoor environments.
Fogging is another use of distance fog in mid-to-late nineties games, where processing power was not enough to render far viewing distances, and clipping was employed. However, the effect could be very distracting, and by applying a medium-ranged fog, the clipped polygons would fade in more realistically from the haze, even though the effect may have been considered unrealistic in some cases. Many early Nintendo 64 games used this effect — most (in)famously in Turok: Dinosaur Hunter and Superman 64.
