Distance fog is a technique used in 3D computer graphics

3D computer graphics

3D computer graphics are graphics that use a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images...

 to enhance the perception

Depth perception

Depth perception is the visual ability to perceive the world in three dimensions and the distance of an object. Depth sensation is the ability to move accurately, or to respond consistently, based on the distances of objects in an environment....

 of distance by simulating fog

Fog

Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of stratus cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated...

.

Because many of the shapes in graphical environments are relatively simple, and complex shadow

Shadow

A shadow is an area where direct light from a light source cannot reach due to obstruction by an object. It occupies all of the space behind an opaque object with light in front of it. The cross section of a shadow is a two-dimensional silhouette, or reverse projection of the object blocking the...

s are difficult to render

Rendering (computer graphics)

Rendering is the process of generating an image from a model , by means of computer programs. A scene file contains objects in a strictly defined language or data structure; it would contain geometry, viewpoint, texture, lighting, and shading information as a description of the virtual scene...

, many graphics engine

Graphics engine

Graphics engine may refer to:*Game engine: a physics model typically implemented in software for use in computer games*Graphics engine : a specialized computer hardware device, typically integrated with a framebuffer or other video display circuitry, for performing graphics calculations...

s employ a "fog" gradient

Gradient

In vector calculus, the gradient of a scalar field is a vector field that points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....

 so objects further from the camera are progressively more obscured by haze

Haze

Haze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. The World Meteorological Organization manual of codes includes a classification of horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic...

 and by aerial perspective

Aerial perspective

Aerial perspective or atmospheric perspective refers to the effect the atmosphere has on the appearance of an object as it is viewed from a distance. As the distance between an object and a viewer increases, the contrast between the object and its background decreases, and the contrast of any...

. This technique simulates the effect of light scattering

Diffraction

Diffraction refers to various phenomena which occur when a wave encounters an obstacle. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665...

, which causes more distant objects to appear lower in contrast

Contrast (vision)

Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...

, especially in outdoor environments.

"Fogging" is another use of distance fog in mid-to-late nineties

1990s

File:1990s decade montage.png|From left, clockwise: The Hubble Space Telescope floats in space after it was taken up in 1990; American F-16s and F-15s fly over burning oil fields and the USA Lexie in Operation Desert Storm, also known as the 1991 Gulf War; The signing of the Oslo Accords on...

 games, when processing power was not enough to render far viewing distances

Draw distance

Draw distance is a computer graphics term, defined as the maximum distance of objects in a three dimensional scene that are drawn by the rendering engine. Polygons that lie behind the draw distance won't be drawn to the screen....

, and clipping

Clipping (computer graphics)

Any procedure which identifies that portion of a picture which is either inside or outside a picture is referred to as a clipping algorithm or clipping.The region against which an object is to be clipped is called clipping window.-Examples:...

 was employed. However, the effect could be very distracting since bits and pieces of polygons would flicker in and out of view instantly, and by applying a medium-ranged fog, the clipped polygon

Polygon

In geometry a polygon is a flat shape consisting of straight lines that are joined to form a closed chain orcircuit.A polygon is traditionally a plane figure that is bounded by a closed path, composed of a finite sequence of straight line segments...

s would fade in more realistically from the haze, even though the effect may have been considered unrealistic in some cases (such as dense fog inside of a building). Many early Nintendo 64

Nintendo 64

The , often referred to as N64, was Nintendo′s third home video game console for the international market. Named for its 64-bit CPU, it was released in June 1996 in Japan, September 1996 in North America, March 1997 in Europe and Australia, September 1997 in France and December 1997 in Brazil...

 and PlayStation

PlayStation

The is a 32-bit fifth-generation video game console first released by Sony Computer Entertainment in Japan on December 3, .The PlayStation was the first of the PlayStation series of consoles and handheld game devices. The PlayStation 2 was the console's successor in 2000...

 games used this effect, as in Turok: Dinosaur Hunter

Turok: Dinosaur Hunter

Turok: Dinosaur Hunter is a first-person shooter video game developed by Iguana Entertainment and published by Acclaim for the Nintendo 64 console and personal computer platforms. It was released in 1997 in North America and Europe. Turok is an adaptation of the Acclaim Comics comic book series of...

, Bubsy 3D

Bubsy 3D

Bubsy 3D: Furbitten Planet, known simply as Bubsy 3D, is a platform video game developed by Eidetic and published by Accolade and Telstar for the PlayStation video game console. It was designed by Michael Berlyn. It was released on October 13, 1996 in North America and in August of 1997 in Europe...

, Star Wars: Rogue Squadron

Star Wars: Rogue Squadron

Star Wars: Rogue Squadron is an arcade-style action game co-developed by Factor 5 and LucasArts. The first of three games in the Rogue Squadron series, it was published by LucasArts and Nintendo and released for Windows and the Nintendo 64 in December 1998...

, Tony Hawk's Pro Skater

Tony Hawk's Pro Skater

-Reception:The game was very well-received by most critics, scoring an outstanding 92 on Metacritic based on 18 reviews for the PS1 version. IGN gave the N64 version of the game a 9.1 out of 10 praising the gameplay for "genius control, combo system and design" despite little criticism with sound...

, and Superman. The game Silent Hill

Silent Hill

is a survival horror video game series consisting of seven installments published by Konami and its subsidiary Konami Digital Entertainment. The first four games in the series, Silent Hill, Silent Hill 2, 3 and 4, have been developed by an internal factor, Team Silent...

uniquely worked fogging into the game's storyline, with the eponymous town being consumed by a dense layer of fog as the result of the player having entered an alternate reality. The application of fogging was so well received as an atmospheric technique that it has appeared in each of the game's sequels, despite advanced technology negating it as a graphical necessity.