2.5D
Encyclopedia
2.5D 3/4 perspective and pseudo-3D are terms used to describe either:
  • 2D graphical projections
    2D computer graphics
    2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models and by techniques specific to them...

     and techniques which cause a series of images or scenes to fake or appear to be three-dimensional (3D) when in fact they are not, or
  • gameplay
    Gameplay
    Gameplay is the specific way in which players interact with a game, and in particular with video games. Gameplay is the pattern defined through the game rules, connection between player and the game, challenges and overcoming them, plot and player's connection with it...

     in an otherwise three-dimensional video game that is restricted to a two-dimensional plane.


Common in video games, these projections have also been useful in geographic visualization (GVIS) to help understand visual-cognitive spatial representations or 3D visualization.

The terms 3/4 perspective and 3/4 view trace their origins to portrait
Portrait
thumb|250px|right|Portrait of [[Thomas Jefferson]] by [[Rembrandt Peale]], 1805. [[New-York Historical Society]].A portrait is a painting, photograph, sculpture, or other artistic representation of a person, in which the face and its expression is predominant. The intent is to display the likeness,...

ure and facial recognition
Face perception
Face perception is the process by which the brain and mind understand and interpret the face, particularly the human face.The human face's proportions and expressions are important to identify origin, emotional tendencies, health qualities, and some social information. From birth, faces are...

, where they are used to describe a view of a person's face which is partway between a frontal view and a side view.

Axonometric & oblique projection

In axonometric projection
Axonometric projection
Axonometric projection is a type of parallel projection, more specifically a type of orthographic projection, used to create a pictorial drawing of an object, where the object is rotated along one or more of its axes relative to the plane of projection....

 and oblique projection
Oblique projection
Oblique projection is a simple type of graphical projection used for producing pictorial, two-dimensional images of three-dimensional objects.- Overview :Oblique projection is a type of parallel projection:...

, two forms of parallel projection
Parallel projection
Parallel projections have lines of projection that are parallel both in reality and in the projection plane.Parallel projection corresponds to a perspective projection with an infinite focal length , or "zoom".Within parallel projection there is an ancillary category known as "pictorials"...

, the viewpoint is rotated slightly to reveal other facets of the environment than what are visible in a top-down perspective or side view, thereby producing a three-dimensional effect. An object is "considered to be in an inclined position resulting in foreshortening of all three axes", and the image is a "representation on a single plane (as a drawing surface) of a three-dimensional object placed at an angle to the plane of projection." Lines perpendicular to the plane become points, lines parallel to the plane have true length, and lines inclined to the plane are foreshortened.

They are popular camera perspectives among 2D
2D computer graphics
2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models and by techniques specific to them...

 video games, most commonly those released for 16-bit
History of video game consoles (fourth generation)
In the history of computer and video games, the fourth generation began on October 30, 1987 with the Japanese release of Nippon Electric Company's PC Engine...

 or earlier and handheld consoles
Handheld console game
A handheld video game is a video game designed for a handheld device. In the past, this primarily meant handheld game consoles such as Nintendo's Game Boy line...

, as well as in later strategy
Strategy video game
Strategy video games is a video game genre that emphasizes skillful thinking and planning to achieve victory. They emphasize strategic, tactical, and sometimes logistical challenges. Many games also offer economic challenges and exploration...

 and role-playing video game
Role-playing video game
Role-playing video games are a video game genre with origins in pen-and-paper role-playing games such as Dungeons & Dragons, using much of the same terminology, settings and game mechanics. The player in RPGs controls one character, or several adventuring party members, fulfilling one or many quests...

s. The advantage of these perspectives are that they combine the visibility and mobility of a top-down game with the character recognizability of a side-scrolling game
Side-scrolling video game
A side-scrolling game or side-scroller is a video game in which the gameplay action is viewed from a side-view camera angle, and the onscreen characters generally move from the left side of the screen to the right. These games make use of scrolling computer display technology...

. Thus the player can be presented an overview of the game world in the ability to see it from above, more or less, and with additional details in artwork made possible by using an angle: Instead of showing a humanoid in top-down perspective, as a head and shoulders seen from above, the entire body can be drawn when using a slanted angle; Turning a character around would reveal how it looks from the sides, the front and the back, while the top-down perspective will display the same head and shoulders regardless.
There are three main divisions of axonometric projection: isometric (equal measure), dimetric (symmetrical and unsymmetrical), and trimetric (single-view or only two sides). The most common of these drawing types in engineering drawing
Engineering drawing
An engineering drawing, a type of technical drawing, is used to fully and clearly define requirements for engineered items.Engineering drawing produces engineering drawings . More than just the drawing of pictures, it is also a language—a graphical language that communicates ideas and information...

 is isometric projection. This projection is tilted so that all three axes create equal angles at intervals of 120 degrees. The result is that all three axes are equally foreshortened. In video games, a form of dimetric projection with a 2:1 pixel ratio is more common due to the problems of anti-aliasing and square pixels found on most computer monitors.

In oblique projection
Oblique projection
Oblique projection is a simple type of graphical projection used for producing pictorial, two-dimensional images of three-dimensional objects.- Overview :Oblique projection is a type of parallel projection:...

 typically all three axes are shown unforeshortened. All lines parallel to the axes are drawn to scale, and diagonals and curved lines are distorted. One tell-tale sign of oblique projection is that the face pointed toward the camera retains its right angles with respect to the image plane.

Two of the most consistent examples of oblique projection are the The Legend of Zelda series of games for the Game Boy
Game Boy
The , is an 8-bit handheld video game device developed and manufactured by Nintendo. It was released in Japan on , in North America in , and in Europe on...

, Game Boy Color
Game Boy Color
The is Nintendo's successor to the 8-bit Game Boy handheld game console, and was released on October 21, 1998 in Japan, November 19, 1998 in North America, November 23, 1998 in Europe and November 27, 1998 in the United Kingdom. It features a color screen and is slightly thicker and taller than...

, and Game Boy Advance
Game Boy Advance
The is a 32-bit handheld video game console developed, manufactured, and marketed by Nintendo. It is the successor to the Game Boy Color. It was released in Japan on March 21, 2001; in North America on June 11, 2001; in Australia and Europe on June 22, 2001; and in the People's Republic of China...

; and the Pokémon
Pokémon (video games)
Pokémon is a series of video games developed by Game Freak and Creatures Inc. and published by Nintendo as part of the Pokémon media franchise. First released in 1996 in Japan for the Game Boy, the main series of role-playing video games has continued on each generation of Nintendo's handhelds...

series for the Nintendo DS
Nintendo DS
The is a portable game console produced by Nintendo, first released on November 21, 2004. A distinctive feature of the system is the presence of two separate LCD screens, the lower of which is a touchscreen, encompassed within a clamshell design, similar to the Game Boy Advance SP...

. Examples of axonometric projection include the latter games in the SimCity series, and role-playing games such as Diablo
Diablo (video game)
Diablo is a dark fantasy-themed action role-playing game developed by Blizzard North and released by Blizzard Entertainment on December 31, 1996....

and Baldur's Gate
Baldur's Gate
Baldur's Gate is a computer role-playing game developed by BioWare and released in 1998 by Interplay Entertainment. The game takes place in the Forgotten Realms, a high fantasy campaign setting, using modified Advanced Dungeons & Dragons 2nd edition rules...

.

Billboarding

In three-dimensional scenes, the term billboarding is applied to a technique in which objects are sometimes represented by two-dimensional images applied to a single polygon which is typically kept perpendicular to the line of sight. The name refers to the fact that objects are seen as if drawn on a billboard
Billboard
Billboard is a weekly American magazine devoted to the music industry, and is one of the oldest trade magazines in the world. It maintains several internationally recognized music charts that track the most popular songs and albums in various categories on a weekly basis...

. This can be used to good effect for a significant performance boost when the geometry is sufficiently distant that it can be seamlessly replaced with a 2D sprite
Sprite (computer graphics)
In computer graphics, a sprite is a two-dimensional image or animation that is integrated into a larger scene...

. In games, this technique is most frequently applied to object such as particles (smoke, sparks, rain) and low-detail vegetation. Other examples include early first-person shooters like Doom and Hexen
Hexen
Hexen is a first-person shooter video game developed by Raven Software, published by id Software, and distributed by GT Interactive beginning on September 30, 1995. It is the sequel to 1994's Heretic, and the second game in the Serpent Riders series...

.

In 3D, polygonal virtual worlds, geometry that is sufficiently distant can be seamlessly replaced with a 2D sprite
Sprite (computer graphics)
In computer graphics, a sprite is a two-dimensional image or animation that is integrated into a larger scene...

 for a significant performance boost. A pioneer in the use of this technique was the game Jurassic Park: Trespasser
Jurassic Park: Trespasser
Jurassic Park: Trespasser is a video game released in 1998 for Microsoft Windows after much hype and anticipation. The player assumes the role of Anne, the sole survivor of a plane crash on InGen's "Site B" one year after the events of The Lost World: Jurassic Park...

. It has since become mainstream, and is found in many games such as Rome: Total War
Rome: Total War
Rome: Total War is a PC strategy game developed by The Creative Assembly and released on by Activision...

, where it is exploited to simultaneously display thousands of individual soldiers on a battlefield.

Skyboxes & skydomes

Skyboxes and skydomes are methods used to easily create a background to make a game level
Level (computer and video games)
A level, map, area, or world in a video game is the total space available to the player during the course of completing a discrete objective...

 look bigger than it really is. If the level is enclosed in a cube, the sky, distant mountains, distant buildings, and other unreachable objects are rendered onto the cube's faces using a technique called cube mapping
Cube mapping
In computer graphics, cube mapping is a method of environment mapping that uses a six-sided cube as the map shape. The environment is projected onto the six faces of a cube and stored as six square textures, or unfolded into six regions of a single texture...

, thus creating the illusion of distant three-dimensional surroundings. A skydome employs the same concept but uses a sphere
Sphere
A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...

 or hemisphere
Sphere
A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...

 instead of a cube.

As a viewer moves through a 3D scene, it is common for the skybox or skydome to remain stationary with respect to the viewer. This technique gives the skybox the illusion of being very far away since other objects in the scene appear to move, while the skybox does not. This imitates real life, where distant objects such as clouds, stars and even mountains appear to be stationary when the viewpoint is displaced by relatively small distances. Effectively, everything in a skybox will always appear to be infinitely distant from the viewer. This consequence of skyboxes dictates that designers should be careful not to carelessly include images of discrete objects in the textures of a skybox since the viewer may be able to perceive the inconsistencies of those objects' sizes as the scene is traversed.

Scaling along the Z axis

In some games, sprites are scaled larger or smaller depending on its distance to the player, producing the illusion of motion along the Z (forward) axis. Sega
Sega
, usually styled as SEGA, is a multinational video game software developer and an arcade software and hardware development company headquartered in Ōta, Tokyo, Japan, with various offices around the world...

's 1986 video game Out Run
Out Run
is an arcade game released by Sega in 1986. It was designed by Yu Suzuki and Sega-AM2. The game was a critical and commercial success. It is notable for its innovative hardware , pioneering graphics and music, a choice in both soundtrack and route, and its strong theme of luxury and relaxation...

is a good example of this technique, though it was predated by the 1982 Namco
Namco
is a Japanese corporation best known as a former video game developer and publisher. Following a merger with Bandai in September 2005, the two companies' game production assets were spun off into Namco Bandai Games on March 31, 2006. Namco Ltd. was re-established to continue domestic operation of...

 game Pole Position, while the first contenders date back to mid-1970s: Interceptor released by Taito
Taito
Taito may mean:*Taito Corporation, a Japanese developer of video game software and arcade hardware*Taito, Tokyo, a special ward located in Tokyo, Japan*Taito, also known as matai, paramount chiefs according to Fa'a Samoa...

 in 1975, and Moto-Cross
Fonz (arcade)
Fonz is a 1976 arcade racing video game developed by Sega and published by Sega-Gremlin. The game was based on the hit TV show Happy Days and the slogan was "TV's hottest name, Your hottest game." The game itself was simply a rebranded variant of Sega's earlier 1976 game Moto-Cross in a customized...

(re-branded as Fonz
Fonz (arcade)
Fonz is a 1976 arcade racing video game developed by Sega and published by Sega-Gremlin. The game was based on the hit TV show Happy Days and the slogan was "TV's hottest name, Your hottest game." The game itself was simply a rebranded variant of Sega's earlier 1976 game Moto-Cross in a customized...

that same year) and Road Race released by Sega in 1976.

In Out Run, the player drives a Ferrari into depth of the game window. The palms on the left and right side of the street are the same bitmap
Bitmap
In computer graphics, a bitmap or pixmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits, a spatially mapped array of bits. Now, along with pixmap, it commonly refers to...

, but have been scaled to different sizes, creating the illusion that some are closer than others. The angles of movement are left and right and into the depth (while still capable of doing so technically, this game did not allow making a U-turn or going into reverse, therefore moving out of the depth, as this did not make sense to the high-speed game play and tense time limit). Notice the view is comparable to that which a driver would have in reality
Reality
In philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...

 when driving a car. The position and size of any billboard is generated by a (complete 3D) perspective transformation as are the vertices of the poly-line representing the center of the street. Often the center of the street is stored as a spline and sampled in a way that on straight streets every sampling point corresponds to one scan-line on the screen. Hills and curves lead to multiple points on one line and one has to be chosen. Or one line is without any point and has to be interpolated lineary from the adjacent lines. Very memory intensive billboards are used in Out Run to draw corn-fields and water waves which are wider than the screen even at the largest viewing distance and also in Test Drive
Test Drive (video game)
Test Drive is a series of racing video games. Originally published by Accolade, which was later bought by Infogrames, the first game was released in 1987 and has since been followed by several sequels...

 to draw trees and cliffs.

Drakkhen
Drakkhen
Drakkhen is a 3D computer role-playing game which was initially developed for the Amiga and Atari ST, and subsequently ported to several other platforms, including MS-DOS and the Super Nintendo Entertainment System....

was notable for being among the first role-playing game
Role-playing game
A role-playing game is a game in which players assume the roles of characters in a fictional setting. Players take responsibility for acting out these roles within a narrative, either through literal acting, or through a process of structured decision-making or character development...

s to feature a three-dimensional playing field. However, it did not employ a conventional 3D game engine, instead emulating one using character-scaling algorithms. The player's party travels overland on a flat terrain made up of vectors, on which 2D objects are zoomed. Drakkhen features an animated day-night cycle, and the ability to wander freely about the game world, both rarities for a game of its era. This type of engine was later used in the game Eternam.

When Duke Nukem 3D
Duke Nukem 3D
Duke Nukem 3D is a first-person shooter computer game developed by 3D Realms and published by GT Interactive Software. The full version was released for the PC . It is a sequel to the platform games Duke Nukem and Duke Nukem II published by Apogee...

was converted to the Game.com
Game.com
The Game.com is a handheld game console released by Tiger Electronics in September 1997. It featured many new ideas for handheld consoles and was aimed at an older target audience, sporting PDA-style features and functions such as a touch screen and stylus...

 console in 1996, the more conventional 2.5D game engine
Build engine
The Build engine is a first-person shooter engine created by Ken Silverman for 3D Realms. Like the Doom engine, the Build engine represents its world on a two-dimensional grid using closed 2D shapes called sectors, and uses simple flat objects called sprites to populate the world geometry with...

 of the game was scrapped for a lower resource version. Thus unlike every other version of the game, Duke Nukem
Duke Nukem (character)
Duke Nukem is a fictional character and action hero who has been the protagonist in over a dozen video games.The character first appeared in the 1991 video game Duke Nukem developed by Apogee Software...

 cannot turn; he can only move forwards, backwards, and strafe left or right whilst scaling the graphics larger and smaller. This implementation was first-person rather than third-person like Drakkhen and the game was marketed as having "3D-style" graphics.

Parallax scrolling


Parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...

ing refers to when a collection of 2D
2D computer graphics
2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models and by techniques specific to them...

 sprite
Sprite (computer graphics)
In computer graphics, a sprite is a two-dimensional image or animation that is integrated into a larger scene...

s or layers of sprites are made to move independently of each other and/or the background to create a sense of added depth. The technique grew out of the multiplane camera
Multiplane camera
The multiplane camera is a special motion picture camera used in the traditional animation process that moves a number of pieces of artwork past the camera at various speeds and at various distances from one another...

 technique used in traditional animation
Traditional animation
Traditional animation, is an animation technique where each frame is drawn by hand...

 since the 1940s.

This type of graphical effect was first used in the 1982 arcade game
Arcade game
An arcade game is a coin-operated entertainment machine, usually installed in public businesses such as restaurants, bars, and amusement arcades. Most arcade games are video games, pinball machines, electro-mechanical games, redemption games, and merchandisers...

 Moon Patrol
Moon Patrol
is a classic arcade game by Irem that was first released in 1982. It was licensed to Williams for distribution in North America.The player controls a moon buggy, viewing it from the side, that travels over the moon's surface. While driving it, obstacles such as craters and mines must be avoided....

. Mode 7
Mode 7
Mode 7 is a graphics mode on the Super NES video game console that allows a background layer to be rotated and scaled on a scanline-by-scanline basis to create many different effects. The most famous of these effects this can create is the application of a perspective effect on a background layer...

, a display system effect that included rotation and scaling, allowed for a 3D effect while moving in any direction without any actual 3D models, and was used to simulate 3D graphics on systems such as the SNES
Super Nintendo Entertainment System
The Super Nintendo Entertainment System is a 16-bit video game console that was released by Nintendo in North America, Europe, Australasia , and South America between 1990 and 1993. In Japan and Southeast Asia, the system is called the , or SFC for short...

. Examples include Sonic the Hedgehog, Street Fighter II
Street Fighter II
is a competitive fighting game originally released for the arcades in . It is the arcade sequel to the original Street Fighter released in and was Capcom's fourteenth title that ran on the CP System arcade hardware...

and Dracula X Chronicles.

Bump, normal & parallax mapping

Bump mapping, normal mapping and parallax mapping are techniques applied to textures
Texture mapping
Texture mapping is a method for adding detail, surface texture , or color to a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Dr Edwin Catmull in his Ph.D. thesis of 1974.-Texture mapping:...

 in 3D rendering
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...

 applications such as video games to simulate bumps and wrinkles on the surface of an object without using more polygon
Polygonal modeling
In 3D computer graphics, polygonal modeling is an approach for modeling objects by representing or approximating their surfaces using polygons. Polygonal modeling is well suited to scanline rendering and is therefore the method of choice for real-time computer graphics...

s. To the end user, this means that textures such as stone walls will have more apparent depth and thus greater realism with less of an influence on the performance of the simulation.

Bump mapping is achieved by perturbing the surface normal
Surface normal
A surface normal, or simply normal, to a flat surface is a vector that is perpendicular to that surface. A normal to a non-flat surface at a point P on the surface is a vector perpendicular to the tangent plane to that surface at P. The word "normal" is also used as an adjective: a line normal to a...

s of an object and using a grayscale
Grayscale
In photography and computing, a grayscale or greyscale digital image is an image in which the value of each pixel is a single sample, that is, it carries only intensity information...

 image and the perturbed normal during illumination calculations. The result is an apparently bumpy surface rather than a perfectly smooth surface although the surface of the underlying object is not actually changed. Bump mapping was introduced by Blinn in 1978.
In normal mapping, the unit vector from the shading point to the light source is dotted
Dot product
In mathematics, the dot product or scalar product is an algebraic operation that takes two equal-length sequences of numbers and returns a single number obtained by multiplying corresponding entries and then summing those products...

 with the unit vector normal to that surface, and the result is the intensity of the light on that surface. Imagine a polygonal model of a sphere - you can only approximate the shape of the surface. By using a 3-channel bitmapped image textured across the model, more detailed normal vector information can be encoded. Each channel in the bitmap corresponds to a spatial dimension (X, Y and Z). These spatial dimensions are relative to a constant coordinate system for object-space normal maps, or to a smoothly varying coordinate system (based on the derivatives of position with respect to texture coordinates) in the case of tangent-space normal maps. This adds much more detail to the surface of a model, especially in conjunction with advanced lighting techniques.

Parallax mapping (also called offset mapping or virtual displacement mapping) is an enhancement of the bump mapping and normal mapping techniques implemented by displacing the texture coordinates at a point on the rendered polygon by a function of the view angle in tangent space (the angle relative to the surface normal) and the value of the height map at that point. At steeper view-angles, the texture coordinates are displaced more, giving the illusion of depth due to parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...

 effects as the view changes.

Film and animation techniques

The term is also used to describe an animation
Animation
Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement. The effect is an optical illusion of motion due to the phenomenon of persistence of vision, and can be created and demonstrated in several ways...

 effect commonly used in music videos and, more frequently, title sequences. Brought to wide attention by the motion picture The Kid Stays in the Picture
The Kid Stays in the Picture
The Kid Stays in the Picture is the name of a 1994 autobiography by film producer Robert Evans. It is also the name of a 2002 film adaptation of the book directed by Nanette Burstein and Brett Morgen and released by Focus Features and USA Pictures...

based on the book by film producer Robert Evans
Robert Evans (film producer)
Robert Evans is an American film producer, best known for his work on Rosemary's Baby, Love Story, The Godfather, and Chinatown.-Early life and acting career:...

, it involves the layering and animating of two-dimensional pictures in three dimensional space. Earlier examples of this technique include Liz Phair
Liz Phair
Phair's entry into the music industry began when she met guitarist Chris Brokaw, a member of the band Come. Brokaw and Phair moved to San Francisco together, and Phair tried to become an artist there...

's music video "Down" directed by Rodney Ascher and "A Special Tree" directed by musician Giorgio Moroder
Giorgio Moroder
Hansjörg "Giorgio" Moroder is an Italian record producer, songwriter and performer based in Los Angeles. When in Munich in the 1970s, he started his own record label called Oasis Records, which several years later became a subdivision of Casablanca Records...

 and starring actor Adam Baldwin
Adam Baldwin
Adam Baldwin is an American actor, known for his roles as Animal Mother in Stanley Kubrick's Full Metal Jacket, Ricky Linderman in My Bodyguard, Knowle Rohrer in The X-Files, and Marcus Hamilton in Joss Whedon's Angel...

.

Graphic design

The term also refers to an often-used effect in the design of icon
Icon (computing)
A computer icon is a pictogram displayed on a computer screen and used to navigate a computer system or mobile device. The icon itself is a small picture or symbol serving as a quick, intuitive representation of a software tool, function or a data file accessible on the system. It functions as an...

s and graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

s (GUIs), where a slight 3D illusion is created by the presence of a virtual light source to the left (or in some cases right) side, and above a person's computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

 monitor
Computer display
A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...

. The light source itself is always invisible, but its effects are seen in the lighter colors for the top and left side, simulating reflection, and the darker colours to the right and below of such objects, simulating shadow.

An advanced version of this technique can be found in some specialised graphic design software, such as Pixologic's ZBrush
ZBrush
ZBrush is a digital sculpting tool that combines 3D/2.5D modeling, texturing and painting. It uses a proprietary "pixol" technology which stores lighting, color, material, and depth information for all objects on the screen...

. The idea is that the program's canvas represents a normal 2D painting surface, but that the data structure that holds the pixel information is also able to store information with respect to a z-index, as well material settings, specularity, etc. Again, with this data it is thus possible to simulate lighting, shadows, and so forth.

3D games with a two-dimensional playing field

The term "2.5D" is also applied to 3D games that use polygonal graphics to render the world and/or characters, but whose gameplay is restricted to a 2D plane. Examples include Pandemonium
Pandemonium (video game)
Pandemonium! is a platform game, for the PlayStation, Sega Saturn, Microsoft Windows, N-Gage, and iPhone OS. It features Fargus, a joker, and Nikki, who unwittingly casts a spell that destroys the town. The goal of the game is to reach the Wishing Engine, where they can wish the town back to...

, Klonoa: Door to Phantomile
Klonoa: Door to Phantomile
is a 1997 platform game developed and published by Namco for the PlayStation. The game's story focuses on an anthropomorphic creature and a "spirit" encapsulated in a ring. The game was critically praised, with high sales in Japan, but low sales elsewhere. The game was followed by a sequel, Klonoa...

, Nights into Dreams...
NiGHTS into Dreams...
Nights into Dreams... , is a video game released by Sega in 1996 for the Sega Saturn video game system. The game's story follows two children entering a dream world, where they are aided by the main character, Nights...

, Yoshi's Story
Yoshi's Story
is a side-scrolling platform game, published and developed by Nintendo for the Nintendo 64 entertainment system. It is the sequel to the Super Nintendo game Super Mario World 2: Yoshi's Island. It was released on December 21, 1997 in Japan, March 1, 1998 in North America and April 9, 1998 in Europe...

, Viewtiful Joe
Viewtiful Joe
is a video game developed by Capcom's Production Studio 4 for the Nintendo GameCube. It was originally released in 2003 as a part of the Capcom Five under director Hideki Kamiya and producer Atsushi Inaba. Viewtiful Joe was later ported to the Sony PlayStation 2 by the same design team under the...

, Shadow Complex
Shadow Complex
Shadow Complex is a platform-adventure video game developed by Chair Entertainment in association with Epic Games and published by Microsoft Game Studios for Xbox Live Arcade, and is powered by Unreal Engine 3...

, Strider 2
Strider 2
Strider 2, released in Japan as , is Capcom's 1999 sequel to the original Strider. The game is actually the second sequel to Strider produced, following the U.S. Gold-produced Strider Returns released in , a game with which Capcom was not directly involved...

, Kirby 64: The Crystal Shards
Kirby 64: The Crystal Shards
Kirby 64: The Crystal Shards, known as in Japan, is a platform game developed by HAL Laboratory and published by Nintendo for the Nintendo 64...

, Duke Nukem: Manhattan Project
Duke Nukem: Manhattan Project
Duke Nukem: Manhattan Project is a platform game developed by Sunstorm Interactive, produced by 3D Realms, and published by Arush Entertainment. It was released on Microsoft Windows on May 14, 2002 in North America and on June 14, 2002 in Europe...

, Tomba!
Tomba!
Tomba! is a side-scrolling adventure game created by Whoopee Camp Co. Ltd. for the Sony PlayStation. Tomba! was followed by a sequel titled Tomba! 2: The Evil Swine Return. The imaginative atmosphere and innovative gameplay of Tomba! has continued to keep it nostalgically popular with gamers...

, The Simpsons Game
The Simpsons Game
The Simpsons Game is an action/platformer video game based on the animated television series The Simpsons, made for the Wii, PlayStation 3, Xbox 360, PlayStation 2, Nintendo DS, and PlayStation Portable. The game was developed, published, and distributed by Electronic Arts. It was released in North...

 (DS)
, New Super Mario Bros.
New Super Mario Bros.
is a side-scrolling platform video game published and developed by Nintendo for the Nintendo DS handheld game console. The game was released in North America and Japan in May 2006 and in Australia and Europe in June 2006...

, Sonic Rivals
Sonic Rivals
Sonic Rivals is a game in the Sonic the Hedgehog series in late 2006. It is the first Sonic game developed by a Canadian company, Backbone Entertainment exclusively for the PlayStation Portable...

, Sonic Rush
Sonic Rush
is a 2005 platform handheld video game developed by Sonic Team and Dimps exclusively for the Nintendo DS as part of Sega's Sonic the Hedgehog series. It was released on November 15, 2005 in North America, November 18 in the PAL region, and November 23 in Japan. It is a 2D platform game, but Sonic's...

, Bionic Commando Rearmed
Bionic Commando Rearmed
Bionic Commando Rearmed is an enhanced remake of the 1988 Nintendo Entertainment System version of Bionic Commando. It was developed by GRIN and published by Capcom for Microsoft Windows, PlayStation Network, and Xbox Live Arcade and was released on August 13, 2008...

, New Super Mario Bros. Wii
New Super Mario Bros. Wii
is a 2009 side-scrolling platform video game published and developed by Nintendo for the Wii video game console. The game was released on November 12, 2009 in Australia, November 15, 2009 in North America, November 20, 2009 in Europe and December 3, 2009 in Japan...

"Kirby's Return to Dream Land
Kirby's Return to Dream Land
Kirby's Return to Dream Land, known in Japan as and in Europe and Australia as Kirby's Adventure Wii, is a Kirby video game and the twelveth platform installment of the series, in development by HAL Laboratory, and published by Nintendo...

" and Donkey Kong Country Returns
Donkey Kong Country Returns
Donkey Kong Country Returns, known as in Japan, is a side-scrolling 2.5D platform game developed by Retro Studios and released by Nintendo for the Wii console on November 21, 2010, in North America, December 3, 2010, in Europe, and on December 9, 2010, in Japan...

. The Crash Bandicoot series
Crash Bandicoot series
Crash Bandicoot is a series of platform video games published by Activision after first being developed by Naughty Dog and published by Sony Computer Entertainment. Initially created by Andy Gavin and Jason Rubin, the series was developed for its first four years by the video game company Naughty...

 is sometimes referred to as 2.5D because although the characters and scenery are rendered in 3D, most of its levels are not as free-roaming like 'true' 3D platformers. Other examples include R-Type Delta
R-Type Delta
R-Type Delta is a horizontally scrolling shooter video game.Released only on the PlayStation, this is the fourth game in the R-Type series , and also the first game offering different fighters, with different Force and Wave Cannon combinations for the player to choose from...

, Sonic Colors
Sonic Colors
is a 2010 platforming game in the Sonic the Hedgehog series. It was first announced on May 26, 2010, in a press release by Sega for Italy, and it included a teaser trailer...

,Sonic 3D, Sonic Unleashed
Sonic Unleashed
Sonic Unleashed , is a video game and the 11th installment in the Sonic the Hedgehog series developed by Sonic Team and published by Sega for multiple platforms...

, Gradius V
Gradius V
Gradius V is a Japanese-developed shoot 'em up video game published by Konami for the Sony PlayStation 2 video game console in 2004. Gradius V was largely developed under contract by the Treasure team responsible for Radiant Silvergun and Ikaruga under supervision of Konami's internal development...

, Contra: Shattered Soldier
Contra: Shattered Soldier
Contra: Shattered Soldier, published in Japan as is a video game that is part of the Contra series by Konami. It was developed by Team Kijirushi, a group of staff members within Konami Computer Entertainment Tokyo, and released for the PlayStation 2 in 2002...

, Castlevania: The Dracula X Chronicles, George of the Jungle and the Search for the Secret
George of the Jungle and the Search for the Secret
George of the Jungle and the Search for the Secret is a video game based on the animated television program George of the Jungle. The game is in 3D but plays like a 2D side scrolling platformer game with 3D turns and camera angles in the environment and the path that George walks on...

, LittleBigPlanet
LittleBigPlanet
LittleBigPlanet, commonly abbreviated LBP, is a puzzle platformer video game, based on user-generated content, for the PlayStation 3 first announced on 7 March 2007, by Phil Harrison at the Game Developers Conference in San Francisco, California...

and Sonic Generations
Sonic Generations
is a 2011 platform video game in the Sonic the Hedgehog series, produced by Sonic Team for PlayStation 3, Xbox 360, Microsoft Windows and Nintendo 3DS...

.

Some fighting games such as the Super Smash Bros. series
Super Smash Bros. series
Super Smash Bros., known in Japan as , is a series of fighting games published by Nintendo, featuring characters from established video games. The gameplay differs from traditional fighters for focusing on knocking opponents out of the stage instead of depleting life bars...

, Marvel Vs. Capcom 3, Street Fighter IV
Street Fighter IV
is a fighting game produced by Capcom. It is the first numbered Street Fighter game released by Capcom since . The coin-operated arcade game was released in Japan on July 18, 2008, with North American arcades importing the machines by August...

, Mortal Kombat and BlazBlue
BlazBlue: Calamity Trigger
is a fighting game developed by Arc System Works. The game's name is a portmanteau of "blaze" and "blue," with the "z" sound omitted in the Japanese pronunciation, rendering it similar to the word "brave" in pronunciation....

also utilize 2.5D to showcase 3D backdrops and/or characters while limiting the action to a 2D plane.

In some games, such as Goemon's Great Adventure
Goemon's Great Adventure
, known as Mystical Ninja 2 Starring Goemon in Europe, is a video game developed and released by Konami for the Nintendo 64 on December 23, 1998. It is the third game in the Ganbare Goemon series released in North America and following Mystical Ninja Starring Goemon, released two years earlier...

and Pandemonium
Pandemonium (video game)
Pandemonium! is a platform game, for the PlayStation, Sega Saturn, Microsoft Windows, N-Gage, and iPhone OS. It features Fargus, a joker, and Nikki, who unwittingly casts a spell that destroys the town. The goal of the game is to reach the Wishing Engine, where they can wish the town back to...

, the area of gameplay can be described as a two-dimensional surface twisting and bending in a three-dimensional space. Inside this surface, the character and physics behave like in a traditional 2D platformer. There are however a number of twists that aren't possible with normal 2D platformers: it is common in such games to let the two-dimensional plane cross itself or other planes on certain points, thus creating "track switches" in the course. Players can explore different areas of the 3D world that way or can be brought back to previous points seamlessy. Interactions with the "background" (non-accessible points in the 3D landscape) are also used extensively.

History

The first video games that used pseudo-3D were primarily arcade game
Arcade game
An arcade game is a coin-operated entertainment machine, usually installed in public businesses such as restaurants, bars, and amusement arcades. Most arcade games are video games, pinball machines, electro-mechanical games, redemption games, and merchandisers...

s, the earliest known examples dating back to the mid-1970s, when they began using microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

s. In 1975, Taito
Taito
Taito may mean:*Taito Corporation, a Japanese developer of video game software and arcade hardware*Taito, Tokyo, a special ward located in Tokyo, Japan*Taito, also known as matai, paramount chiefs according to Fa'a Samoa...

 released Interceptor, an early first-person shooter
First-person shooter
First-person shooter is a video game genre that centers the gameplay on gun and projectile weapon-based combat through first-person perspective; i.e., the player experiences the action through the eyes of a protagonist. Generally speaking, the first-person shooter shares common traits with other...

 and combat flight simulator
Combat flight simulator
Combat flight simulators are video games used to simulate military aircraft and their operations...

 that involved piloting a jet fighter
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...

, using an eight-way joystick
Joystick
A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks, also known as 'control columns', are the principal control in the cockpit of many civilian and military aircraft, either as a center stick or...

 to aim with a crosshair and shoot at enemy aircraft that move in formations of two and increase/decrease in size depending on their distance to the player. In 1976, Sega
Sega
, usually styled as SEGA, is a multinational video game software developer and an arcade software and hardware development company headquartered in Ōta, Tokyo, Japan, with various offices around the world...

 released Moto-Cross
Fonz (arcade)
Fonz is a 1976 arcade racing video game developed by Sega and published by Sega-Gremlin. The game was based on the hit TV show Happy Days and the slogan was "TV's hottest name, Your hottest game." The game itself was simply a rebranded variant of Sega's earlier 1976 game Moto-Cross in a customized...

, an early black-and-white motorbike racing video game, based on the motocross
Motocross
Motocross is a form of motorcycle sport or all-terrain vehicle racing held on enclosed off road circuits. It evolved from trials, and was called scrambles, and later motocross, combining the French moto with cross-country...

 competition, that was most notable for introducing an early three-dimensional third-person perspective. Later that year, Sega-Gremlin
Gremlin Industries
Gremlin Industries was arcade game manufacturer active from the 1970s to early 1980s, and based San Diego, California, USA .Gremlin was founded in 1973 as a manufacturer of coin-operated wall games. Gremlin's first wall game, Play Ball, was fairly successful.- History :Gremlin joined the video game...

 re-branded the game as Fonz
Fonz (arcade)
Fonz is a 1976 arcade racing video game developed by Sega and published by Sega-Gremlin. The game was based on the hit TV show Happy Days and the slogan was "TV's hottest name, Your hottest game." The game itself was simply a rebranded variant of Sega's earlier 1976 game Moto-Cross in a customized...

, as a tie-in for the popular sitcom, Happy Days
Happy Days
Happy Days is an American television sitcom that originally aired from January 15, 1974, to September 24, 1984, on ABC. Created by Garry Marshall, the series presents an idealized vision of life in mid-1950s to mid-1960s America....

. Both versions of the game displayed a constantly changing forward-scrolling road and the player's bike in a third-person perspective where objects nearer to the player are larger than those nearer to the horizon, and the aim was to steer the vehicle across the road, racing against the clock, while avoiding any on-coming motorcycles or driving off the road. That same year also saw the release of two arcade games that extended the car driving
Driving
Driving is the controlled operation and movement of a land vehicle, such as a car, truck or bus.Although direct operation of a bicycle and a mounted animal are commonly referred to as riding, such operators are legally considered drivers and are required to obey the rules of the road...

 subgenre into three dimensions with a first-person
First person (video games)
In video games, first person refers to a graphical perspective rendered from the viewpoint of the player character. In many cases, this may be the viewpoint from the cockpit of a vehicle. Many different genres have made use of first-person perspectives, ranging from adventure games to flight...

 perspective: Sega's Road Race, which displayed a constantly changing forward-scrolling S-shaped road with two obstacle race cars moving along the road that the player must avoid crashing while racing against the clock, and Atari
Atari
Atari is a corporate and brand name owned by several entities since its inception in 1972. It is currently owned by Atari Interactive, a wholly owned subsidiary of the French publisher Atari, SA . The original Atari, Inc. was founded in 1972 by Nolan Bushnell and Ted Dabney. It was a pioneer in...

's Night Driver
Night Driver
Night Driver is a 1976 arcade game by Atari Inc. It was one of the earliest first-person racing games, and is believed to be one of the first published games to display real-time first-person graphics....

, which presented a series of posts by the edge of the road though there was no view of the road or the player's car. Games using vector graphics
Vector graphics
Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon, which are all based on mathematical expressions, to represent images in computer graphics...

 had an advantage in creating pseudo-3D effects. 1979's Speed Freak recreated the perspective of Night Driver in greater detail.

In 1979, Nintendo
Nintendo
is a multinational corporation located in Kyoto, Japan. Founded on September 23, 1889 by Fusajiro Yamauchi, it produced handmade hanafuda cards. By 1963, the company had tried several small niche businesses, such as a cab company and a love hotel....

's Shigeru Miyamoto
Shigeru Miyamoto
is a Japanese video game designer and producer. Miyamoto was born and raised in Kyoto Prefecture; the natural surroundings of Kyoto inspired much of Miyamoto's later work....

 debuted with Radar Scope
Radar Scope
is an early cabinet arcade game developed and published by Nintendo in November 1980. Some sources claim that Ikegami Tsushinki also did design work on Radar Scope. It is a shooter that can be viewed as a cross between Taito's Space Invaders and Namco's Galaxian...

, a shoot 'em up
Shoot 'em up
Shoot 'em up is a subgenre of shooter video games. In a shoot 'em up, the player controls a lone character, often in a spacecraft or aircraft, shooting large numbers of enemies while dodging their attacks. The genre in turn encompasses various types or subgenres and critics differ on exactly what...

 that introduced a three-dimensional third-person perspective to the genre, imitated years later by shooters
Shooter game
Shooter games are a sub-genre of action game, which often test the player's speed and reaction time. It includes many subgenres that have the commonality of focusing "on the actions of the avatar using some sort of weapon. Usually this weapon is a gun, or some other long-range weapon". A common...

 such as Konami
Konami
is a Japanese leading developer and publisher of numerous popular and strong-selling toys, trading cards, anime, tokusatsu, slot machines, arcade cabinets and video games...

's Juno First
Juno First
Juno First is a shoot 'em up arcade game developed by Konami and released in 1983. It was licensed to Gottlieb in the United States. The game is a vertical scrolling shooter, with a third-person perspective like Radar Scope. It follows in the tradition of space-themed shooting-galleries such as...

and Activision
Activision
Activision is an American publisher, majority owned by French conglomerate Vivendi SA. Its current CEO is Robert Kotick. It was founded on October 1, 1979 and was the world's first independent developer and distributor of video games for gaming consoles...

's Beamrider
Beamrider
Beamrider is a scrolling shooter designed for the Intellivision by Activision programmer David Rolfe. The game was then ported to the Atari 2600 , Atari 5200, Atari 8-bit, ColecoVision, Commodore 64, ZX Spectrum as well as the MSX platform.-Summary:Beamrider takes place above Earth's atmosphere,...

. In 1980, Atari's Battlezone was a breakthrough for pseudo-3D gaming, recreating a 3D perspective with unprecedented realism, though the gameplay was still planar. It was followed up that same year by Red Baron, which used scaling vector images to create a forward scrolling rail shooter.

Sega
Sega
, usually styled as SEGA, is a multinational video game software developer and an arcade software and hardware development company headquartered in Ōta, Tokyo, Japan, with various offices around the world...

's arcade shooter Space Tactics, released in 1980, allowed players to take aim using crosshairs and shoot lasers into the screen at enemies coming towards them, creating an early 3D effect. It was followed by other arcade shooters with a first-person perspective during the early 1980s, including Taito
Taito
Taito may mean:*Taito Corporation, a Japanese developer of video game software and arcade hardware*Taito, Tokyo, a special ward located in Tokyo, Japan*Taito, also known as matai, paramount chiefs according to Fa'a Samoa...

's 1981 release Space Seeker, and Sega's Star Trek
Star Trek (arcade game)
Star Trek: Strategic Operations Simulator is a space combat simulation arcade game based on the original Star Trek television program, and released by Sega in 1982. It is a vector game, with both a two-dimensional display and a three-dimensional first-person perspective...

in 1982. Sega's SubRoc-3D
Subroc-3D
SubRoc-3D is an arcade game released in 1982 by Sega, and the first such game to provide a three-dimensional image to the player, using a display that delivers individual images to each eye...

in 1982 also featured a first-person perspective and introduced the use of stereoscopic 3-D through a special eyepiece. Sega's Astron Belt
Astron Belt
Astron Belt is an early laserdisc video game and third-person space combat rail shooter, released in 1983 by Sega in Japan and licensed to Bally Midway for release in the United States. Developed in 1982, it is commonly cited as the first laserdisc game...

in 1983 was the first laserdisc video game
Laserdisc video game
A laserdisc video game is an arcade game that uses pre-recorded video played from a laserdisc, either as the entirety of the graphics, or as part of the graphics.-History:...

, using full-motion video to display the graphics from a first-person perspective. Third-person
Third-person shooter
Third-person shooter is a genre of 3D action games in which the player character is visible on-screen, and the gameplay consists primarily of shooting.-Definition:...

 rail shooters were also released in arcades at the time, including Sega's Tac/Scan
Tac/Scan
Tac/Scan is a 1982 space combat shooter video game originally released as an arcade game, and later ported to the Atari 2600. It was also included as an unlockable game in the PlayStation 2 version of Sega Genesis Collection...

in 1982, Nippon's Ambush in 1983, Nichibutsu
Nihon Bussan
Nihon Bussan Co., Ltd. is a Japanese video game manufacturer, commonly known as Nichibutsu . The company uses an owl sign for the company's official logo. The company has its headquarters in Kita-ku, Osaka....

's Tube Panic in 1983, and Sega's 1982 release Buck Rogers: Planet of Zoom, notable for its fast pseudo-3D scaling and detailed sprites.

In 1981, Sega's Turbo
Turbo (video game)
Turbo is a racing game released in 1981 by Sega. The game was brought into arcades in both the standard upright cabinet format, and a semi-enclosed sit-down version to better simulate driving a real car.. The cars in the game resemble Formula 1 race cars. It was the first game to feature the now...

was the first racing game to feature a third-person perspective, rear view format. It was also the first racing game to use sprite
Sprite (computer graphics)
In computer graphics, a sprite is a two-dimensional image or animation that is integrated into a larger scene...

 scaling with full-colour graphics. Pole Position
Pole Position
Pole Position is a racing video game released in 1982 by Namco. It was published by Namco in Japan and by Atari, Inc. in the United States...

by Namco
Namco
is a Japanese corporation best known as a former video game developer and publisher. Following a merger with Bandai in September 2005, the two companies' game production assets were spun off into Namco Bandai Games on March 31, 2006. Namco Ltd. was re-established to continue domestic operation of...

 is one of the first racing games to use the trailing camera effect that is now so familiar. In this particular example, the effect was produced by linescroll—the practice of scrolling each line
independently in order to warp an image. In this case, the warping would simulate curves and steering. To make the road
appear to move towards the player, per-line color changes were used, though many console versions opted for palette
animation instead.

Zaxxon
Zaxxon
Zaxxon is a 1982 arcade game developed and released by Sega. Some sources claim that Japanese electronics company Ikegami Tsushinki also worked on the development of Zaxxon...

, a shooter introduced by Sega in 1982, was the first game to use isometric axonometric projection
Axonometric projection
Axonometric projection is a type of parallel projection, more specifically a type of orthographic projection, used to create a pictorial drawing of an object, where the object is rotated along one or more of its axes relative to the plane of projection....

, from which its name is derived. Though Zaxxon's playing field is semantically 3D, the game has many constraints which classify it as 2.5D: a fixed point of view, scene composition from sprites, and movements such as bullet shots restricted to straight lines along the axes. It was also one of the first video games to display shadows. The following year, Sega released the first pseudo-3D isometric platformer, Congo Bongo
Congo Bongo
Congo Bongo is an isometric platform arcade game released by Sega in 1983. Strong evidence from analysis of the game's ROM claim that Ikegami Tsushinki also did development work on Congo Bongo. The game has come to be seen as Sega's answer to the highly successful Donkey Kong game that was...

. Another early pseudo-3D platform game
Platform game
A platform game is a video game characterized by requiring the player to jump to and from suspended platforms or over obstacles . It must be possible to control these jumps and to fall from platforms or miss jumps...

 released that year was Konami
Konami
is a Japanese leading developer and publisher of numerous popular and strong-selling toys, trading cards, anime, tokusatsu, slot machines, arcade cabinets and video games...

's Antarctic Adventure
Antarctic Adventure
Antarctic Adventure, known in Japan as Kekkyoku Nankyoku Daibōken is a video game developed by Konami in 1983 for MSX, and later for video game consoles, such as NES...

, where the player controls a penguin in a forward-scrolling third-person perspective while having to jump over pits and obstacles. It was one of the earliest pseudo-3D games available on a computer, released for the MSX
MSX
MSX was the name of a standardized home computer architecture in the 1980s conceived by Kazuhiko Nishi, then Vice-president at Microsoft Japan and Director at ASCII Corporation...

 in 1983. That same year, Irem's Moon Patrol
Moon Patrol
is a classic arcade game by Irem that was first released in 1982. It was licensed to Williams for distribution in North America.The player controls a moon buggy, viewing it from the side, that travels over the moon's surface. While driving it, obstacles such as craters and mines must be avoided....

was a side-scrolling
Side-scrolling video game
A side-scrolling game or side-scroller is a video game in which the gameplay action is viewed from a side-view camera angle, and the onscreen characters generally move from the left side of the screen to the right. These games make use of scrolling computer display technology...

 run & gun platform-shooter that introduced the use of layered parallax scrolling
Parallax scrolling
Parallax scrolling is a special scrolling technique in computer graphics, popularized in the 1982 arcade game Moon Patrol. In this pseudo-3D technique, background images move by the camera slower than foreground images, creating an illusion of depth in a 2D video game and adding to the immersion...

 to give a pseudo-3D effect. In 1985, Space Harrier
Space Harrier
is a third-person rail shooter game, released by Sega in 1985. It was produced by Yu Suzuki, responsible for many popular Sega games. It spawned several sequels: Space Harrier 3-D , Space Harrier II , and the spin-off Planet Harriers ....

introduced Sega's "Super Scaler" technology that allowed pseudo-3D sprite-scaling at high frame rate
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...

s, with the ability to scale 32,000 sprites
Sprite (computer graphics)
In computer graphics, a sprite is a two-dimensional image or animation that is integrated into a larger scene...

 and fill a moving landscape with them.

The first console
Video game console
A video game console is an interactive entertainment computer or customized computer system that produces a video display signal which can be used with a display device to display a video game...

 game to use pseudo-3D, and also the first to use multiple camera angles mirrored on television sports broadcasts, was Intellivision World Series Baseball
Intellivision World Series Baseball
Intellivision World Series Major League Baseball is a baseball sports game , designed by Don Daglow and Eddie Dombrower and published by Mattel for the Intellivision Entertainment Computer System. IWSB was the first video game of any kind to use multiple camera angles, and the first sports game...

(1983) by Don Daglow
Don Daglow
Don Daglow is an American computer game and video game designer, programmer and producer. He is best known for designing a series of pioneering simulation games and role-playing games, as well as the first computer baseball game and the first graphical MMORPG, all between 1971 and 1995...

 and Eddie Dombrower
Eddie Dombrower
Eddie Dombrower is an American computer game and video game designer, programmer and producer. He is best known as the co-creator of the seminal baseball games Earl Weaver Baseball and Intellivision World Series Baseball...

, published by Mattel
Mattel
Mattel, Inc. is the world's largest toy company based on revenue. The products it produces include Fisher Price, Barbie dolls, Hot Wheels and Matchbox toys, Masters of the Universe, American Girl dolls, board games, and, in the early 1980s, video game consoles. The company's name is derived from...

. Its television sports style of display was later adopted by 3D sports game
Sports game
A sports game is a computer or video game that simulates the practice of traditional sports. Most sports have been recreated with a game, including team sports, athletics and extreme sports. Some games emphasize actually playing the sport , whilst others emphasize strategy and organization...

s and is now used by virtually all major team sports titles. In 1984, Sega ported several pseudo-3D arcade games to the Sega SG-1000 console, including a smooth conversion of the third-person pseudo-3D rail shooter Buck Rogers: Planet of Zoom.

With the advent of consoles and computer systems that were able to handle several thousands of 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 (the most basic element of 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...

) per second and the usage of 3D specialized graphics processing unit
Graphics processing unit
A graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...

, pseudo 3D became obsolete. But even today, there are computer systems in production, such as cellphones, which are often not powerful enough to display true 3D graphics, and therefore use pseudo-3D for that purpose. Interestingly, many games from the 1980s' pseudo-3D arcade era and 16-bit console era are ported to these systems, giving the manufactures the possibility to earn revenues from games that are now nearly twenty years old.

By 1989, 2.5D representations were surfaces drawn with depth cues and apart of graphic libraries like GINO. 2.5D was also used in terrain modeling with software packages such as ISM from Dynamic Graphics, GEOPAK from Uniras and the Intergraph DTM system. 2.5D surface techniques gained popularity within the geography community because of its ability to visualize the normal thickness to area ratio used in many geographic models; this ratio was very small and reflected the thinness of the object in relation to its width, which made it the object realistic in a specific plane. These representations were axiomatic in that the entire subsurface domain was not used or the entire domain could not be reconstructed; therefore, it used only a surface and a surface is one aspect not the full 3D identity.

The resurgence of 2.5D or visual analysis, in natural and earth science, has increased the role of computer systems in the creation of spatial information in mapping. GVIS has made real the search for unknowns, real-time interaction with spatial data, and control over map display and has paid particular attention to three-dimensional representations. Efforts in GVIS have attempted to expand higher dimensions and make them more visible; most efforts have focused on "tricking" vision into seeing three dimensions in a 2D plane. Much like 2.5D displays where the surface of a three dimensional object is represented but locations within the solid are distorted or not accessible.

Technical aspects & generalizations

The reason for using pseudo-3D instead of "real" 3D computer graphics is that the system that has to simulate a three dimensional looking graphic is not powerful enough to handle the calculation intensive routines of 3D computer graphics, yet is capable of using tricks of modifying 2D graphics like bitmap
Bitmap
In computer graphics, a bitmap or pixmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits, a spatially mapped array of bits. Now, along with pixmap, it commonly refers to...

s. One of these tricks is to stretch a bitmap more and more, therefore making it larger with each step, as to give the effect of an object coming closer and closer towards the player.

Even simple shading and size of an image could be considered pseudo-3D, as shading makes it look more realistic. If the light in a 2D game were 2D, it would only be visible on the outline, and because outlines are often dark, they would not be very clearly visible. However, any visible shading would indicate the usage of pseudo-3D lighting and that the image uses pseudo-3D graphics. Changing the size of an image can cause the image to appear to be moving closer or further away, which could be considered simulating a third dimension.

Dimensions are the variables of the data and can be mapped to specific locations in space; 2D data can be given 3D volume by adding a value to the x, y, or z plane. "Assigning height to 2D regions of a topographic map" associating every 2D location with a height/elevation value creates a 2.5D projection; this is not considered a "true 3D representation", however is used like 3D visual representation to "simplify visual processing of imagery and the resulting spatial cognition".

See also

  • 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...

  • Isometric graphics in video games
  • List of stereoscopic video games
  • Bas-relief
  • Trompe-l'œil
  • Head-coupled perspective
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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