3D computer graphics

3D computer graphics, or three-dimensional computer graphics (in contrast to 2D computer graphics), are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for the purposes of performing calculations and rendering 2D images. The resulting images may be stored for viewing later (possibly as an animation) or displayed in real time. Unlike 3D film and similar techniques, the result is two-dimensional, without the illusion of being solid.

See also: Computer graphics (computer science) and Computer graphics
Three-dimensional (3D)
computer graphics
Fundamentals
Primary uses
Related topics

3D computer graphics rely on many of the same algorithms as 2D computer vector graphics in the wire-frame model and 2D computer raster graphics in the final rendered display. In computer graphics software, 2D applications may use 3D techniques to achieve effects such as lighting, and, similarly, 3D may use some 2D rendering techniques.

The objects in 3D computer graphics are often referred to as 3D models. Unlike the rendered image, a model's data is contained within a graphical data file. A 3D model is a mathematical representation of any three-dimensional object; a model is not technically a graphic until it is displayed. A model can be displayed visually as a two-dimensional image through a process called 3D rendering, or it can be used in non-graphical computer simulations and calculations. With 3D printing, models are rendered into an actual 3D physical representation of themselves, with some limitations as to how accurately the physical model can match the virtual model.[1]

History
Main article: History of computer animation

William Fetter was credited with coining the term computer graphics in 1961[2][3] to describe his work at Boeing. One of the first displays of computer animation was Futureworld (1976), which included an animation of a human face and a hand that had originally appeared in the 1971 experimental short A Computer Animated Hand, created by University of Utah students Edwin Catmull and Fred Parke.[4]

3D computer graphics software began appearing for home computers in the late 1970s. The earliest known example is 3D Art Graphics, a set of 3D computer graphics effects, written by Kazumasa Mitazawa and released in June 1978 for the Apple II.[5][6]

Overview

3D computer graphics creation falls into three basic phases:

  1. 3D modeling – the process of forming a computer model of an object's shape
  2. Layout and animation – the placement and movement of objects within a scene
  3. 3D rendering – the computer calculations that, based on light placement, surface types, and other qualities, generate the image

Modeling
Main article: 3D modeling

The model describes the process of forming the shape of an object. The two most common sources of 3D models are those that an artist or engineer originates on the computer with some kind of 3D modeling tool, and models scanned into a computer from real-world objects (Polygonal Modeling, Patch Modeling and NURBS Modeling are some popular tools used in 3d modeling). Models can also be produced procedurally or via physical simulation. Basically, a 3D model is formed from points called vertices that define the shape and form polygons. A polygon is an area formed from at least three vertices (a triangle). A polygon of n points is an n-gon.[7] The overall integrity of the model and its suitability to use in animation depend on the structure of the polygons.

Layout and animation
Main article: Computer animation

Before rendering into an image, objects must be laid out in a scene. This defines spatial relationships between objects, including location and size. Animation refers to the temporal description of an object (i.e., how it moves and deforms over time. Popular methods include keyframing, inverse kinematics, and motion capture). These techniques are often used in combination. As with animation, physical simulation also specifies motion.

Materials and textures

Materials and textures are properties that the render engine uses to render the model. One can give the model materials to tell the render engine how to treat light when it hits the surface. Textures are used to give the material color using a color or albedo map, or give the surface features using a bump map or normal map. It can be also used to deform the model itself using a displacement map.

Rendering
Main article: 3D rendering

Rendering converts a model into an image either by simulating light transport to get photo-realistic images, or by applying an art style as in non-photorealistic rendering. The two basic operations in realistic rendering are transport (how much light gets from one place to another) and scattering (how surfaces interact with light). This step is usually performed using 3D computer graphics software or a 3D graphics API. Altering the scene into a suitable form for rendering also involves 3D projection, which displays a three-dimensional image in two dimensions. Although 3D modeling and CAD software may perform 3D rendering as well (e.g., Autodesk 3ds Max or Blender), exclusive 3D rendering software also exists (e.g., OTOY's Octane Rendering Engine, Maxon's Redshift)

Examples of 3D rendering
Far left: A 3D rendering with ray tracing and ambient occlusion using Blender and YafaRay

Center left: A 3d model of a Dunkerque-class battleship rendered with flat shading

Center right: During the 3D rendering step, the number of reflections "light rays" can take, as well as various other attributes, can be tailored to achieve a desired visual effect. Rendered with Cobalt.

Far right: Experience Curiosity, a real-time web application which leverages 3D rendering capabilities of browsers (WebGL)

Software

3D computer graphics software produces computer-generated imagery (CGI) through 3D modeling and 3D rendering or produces 3D models for analytic, scientific and industrial purposes.

File formats
Main article: List of file formats § 3D graphics

There are many varieties of files supporting 3D graphics, for example, Wavefront .obj files and .x DirectX files. With their own unique data structure.

Each file format can be accessed through their own application, such as DirectX files, and Quake. Or through third party standalone program. Or even through manual decompiling.

Modeling
Main article: 3D modeling software

3D modeling software is a class of 3D computer graphics software used to produce 3D models. Individual programs of this class are called modeling applications or modelers.

3D modelers allow users to create and alter models via their 3D mesh. Users can add, subtract, stretch and otherwise change the mesh to their desire. Models can be viewed from a variety of angles, usually simultaneously. Models can be rotated and the view can be zoomed in and out.

3D modelers can export their models to files, which can then be imported into other applications as long as the metadata are compatible. Many modelers allow importers and exporters to be plugged-in, so they can read and write data in the native formats of other applications.

Most 3D modelers contain a number of related features, such as ray tracers and other rendering alternatives and texture mapping facilities. Some also contain features that support or allow animation of models. Some may be able to generate full-motion video of a series of rendered scenes (i.e. animation).

Computer-aided design (CAD)
Main article: Computer-aided design

Computer aided design software may employ the same fundamental 3D modeling techniques that 3D modeling software use but their goal differs. They are used in computer-aided engineering, computer-aided manufacturing, Finite element analysis, product lifecycle management, 3D printing and computer-aided architectural design.

Complementary tools

After producing video, studios then edit or composite the video using programs such as Adobe Premiere Pro or Final Cut Pro at the mid-level, or Autodesk Combustion, Digital Fusion, Shake at the high-end. Match moving software is commonly used to match live video with computer-generated video, keeping the two in sync as the camera moves.

Use of real-time computer graphics engines to create a cinematic production is called machinima.[8]

Communities

There are a multitude of websites designed to help, educate and support 3D graphic artists. Some are managed by software developers and content providers, but there are standalone sites as well. These communities allow for members to seek advice, post tutorials, provide product reviews or post examples of their own work.

Differences with other types of computer graphics

Distinction from photorealistic 2D graphics
See also: Still life § 21st century

Not all computer graphics that appear 3D are based on a wireframe model. 2D computer graphics with 3D photorealistic effects are often achieved without wireframe modeling and are sometimes indistinguishable in the final form. Some graphic art software includes filters that can be applied to 2D vector graphics or 2D raster graphics on transparent layers. Visual artists may also copy or visualize 3D effects and manually render photorealistic effects without the use of filters.

Pseudo-3D and true 3D
Main article: 2.5D

Some video games use restricted projections of three-dimensional environments, such as isometric graphics or virtual cameras with fixed angles, either as a way to improve performance of the game engine, or for stylistic and gameplay concerns. Such games are said to use pseudo-3D graphics. By contrast, games using 3D computer graphics without such restrictions are said to use true 3D.

See also
Graphics and software

Fields of use

References
  1. "3D computer graphics". ScienceDaily. Retrieved 2019-01-19.
  2. "An Historical Timeline of Computer Graphics and Animation". Archived from the original on 2008-03-10. Retrieved 2009-07-22.
  3. "Computer Graphics".
  4. "Pixar founder's Utah-made Hand added to National Film Registry". The Salt Lake Tribune. December 28, 2011. Retrieved January 8, 2012.
  5. "Brutal Deluxe Software". www.brutaldeluxe.fr.
  6. "PROJECTS AND ARTICLES Retrieving Japanese Apple II programs". Archived from the original on 2016-10-05. Retrieved 2017-03-26.
  7. Simmons, Bruce. "n-gon". MathWords. Archived from the original on 2018-12-15. Retrieved 2018-11-30.
  8. "Machinima". Internet Archive. Retrieved 2020-07-12.
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