3D computer graphics

This article is about the process of creating 3-D computer graphics. For information on the study of computer graphics, see Computer graphics (computer science). For other usage, see Computer graphics.

3-D computer graphics, or three-dimensional computer graphics (in contrast to 2-D 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 2-D images. The resulting images may be stored for viewing later (possibly as an animation) or displayed in real time.

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

The objects in 3-D computer graphics are often referred to as 3-D models. Unlike the rendered image, a model's data is contained within a graphical data file. A 3-D 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 3-D rendering, or it can be used in non-graphical computer simulations and calculations. With 3-D printing, models are rendered into an actual 3-D physical representation of themselves, with some limitations as to how accurately the physical model can match the virtual model.

History

Main article: History of computer animation

William Fetter was credited with coining the term computer graphics in 1961 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.

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

Overview

3-D computer graphics creation falls into three basic phases:

1. 3-D 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. 3-D rendering – the computer calculations that, based on light placement, surface types, and other qualities, generate the image

Modeling

Main article: 3-D modeling

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

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 or normal map. It can be also used to deform the model itself using a displacement map.

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.

Rendering

Main article: 3-D 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 3-D computer graphics software or a 3-D graphics API. Altering the scene into a suitable form for rendering also involves 3-D projection, which displays a three-dimensional image in two dimensions. Although 3-D modeling and CAD software may perform 3-D rendering as well (e.g. Autodesk 3ds Max or Blender), exclusive 3-D rendering software also exists.

Examples of 3-D rendering

File:Experience curiosity1.png

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

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

Center right: During the 3-D 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 3-D rendering capabilities of browsers (WebGL)

Software

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

Modeling

Main article: 3-D modeling software

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

3-D modelers allow users to create and alter models via their 3-D 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.

3-D 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 3-D 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 3-D modeling techniques that 3-D modeling software use but their goal differs. They are used in computer-aided engineering, computer-aided manufacturing, Finite element analysis, product lifecycle management, 3-D 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.

Communities

There are a multitude of websites designed to help, educate and support 3-D 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 2-D graphics

See also: Still life § 21st century

Not all computer graphics that appear 3-D are based on a wireframe model. 2-D computer graphics with 3-D 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 2-D vector graphics or 2-D raster graphics on transparent layers. Visual artists may also copy or visualize 3-D effects and manually render photorealistic effects without the use of filters.

Pseudo-3-D and true 3-D

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-3-D graphics. By contrast, games using 3-D computer graphics without such restrictions are said to use true 3-D.

See also

Template:Wikipedia books

Graphics and software

• Glossary of computer graphics
• Comparison of 3-D computer graphics software
• Graphics processing unit (GPU)
• Graphical output devices
• List of 3-D computer graphics software
• List of 3-D modeling software
• List of 3-D rendering software
• Real-time computer graphics
• Reflection (computer graphics)
• Rendering (computer graphics)

Fields of use

• 3-D data acquisition and object reconstruction
• 3-D motion controller
• 3-D projection on 2-D planes
• 3-D reconstruction
• 3-D reconstruction from multiple images
• Anaglyph 3-D
• Computer animation
• Computer vision
• Digital geometry
• Digital image processing
• Game development tool
• Game engine
• Geometry pipelines
• Geometry processing
• Graphics
• Isometric graphics in video games and pixel art
• Level editor
• List of stereoscopic video games
• Medical animation
• Render farm
• SIGGRAPH
• Stereoscopy
• Timeline of computer animation in film and television
• Video game graphics

External links

• A Critical History of Computer Graphics and Animation (Wayback Machine copy)
• How Stuff Works - 3D Graphics
• History of Computer Graphics series of articles (Wayback Machine copy)
• How 3D Works - Explains 3D modeling for an illuminated manuscript