Computer graphics
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- For the ACM SIGGRAPH journal, see Computer Graphics.
Computer graphics (CG) is the field of visual computing, where one utilizes computers both to generate visual images synthetically and to integrate or alter visual and spatial information sampled from the real world.
The first major advance in computer graphics was the development of the Sketchpad in 1962 by Ivan Sutherland.
This field can be divided into several areas: real-time 3D rendering (often used in video games), computer animation, video capture and video creation rendering, special effects editing (often used for movies and television), image editing, and modeling (often used for engineering and medical purposes). Development in computer graphics was first fueled by academic interests and government sponsorship. However, as real-world applications of computer graphics (CG) in broadcast television and movies proved a viable alternative to more traditional special effects and animation techniques, commercial parties have increasingly funded advances in the field.
It is often thought that the first feature film to use computer graphics was 2001: A Space Odyssey, which attempted to show how computers would be much more graphical in the future. However, all the "computer graphic" effects in that film were hand-drawn animation, and the special effects sequences were produced entirely with conventional optical and model effects.
Perhaps the first use of computer graphics specifically to illustrate computer graphics was in Futureworld (1976), which included an animation of a human face and hand - produced by Ed Catmull and Fred Parke at the University of Utah.
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Computer graphics, 2D
The first advance in computer graphics was in the use of CRTs. See 2D computer graphics. There are two approaches to 2D graphics: vector and raster graphics. Vector graphics stores precise geometric data, topology and style such as coordinate positions of points, the connections between points (to form lines or paths) and the colour, thickness and possible fill of the shapes. Most vector graphic systems can also use primitives of standard shapes such as circles and rectangles etc. In most cases a vector graphic image has to be converted to a raster image to be viewed. Raster graphics is a uniform two dimensional grid of pixels. Each pixel has a specific value such as for instance brightness, colour transparancy or a combination of such values. A raster image has a finite resolution of a specific number of rows and columns. Standard computer displays shows a raster image of resolutions such as 1280(columns)x1024(rows) of pixels. Today one often combines raster and vector graphics in compound file formats (pdf,swf).
Computer graphics, 3D
With the birth of the workstation computers (like LISP machines, paintbox computers and Silicon Graphics workstations) came the 3D computer graphics, based on vector or "wire-frame" representations of virtual objects.
Some major advances in 3D computer graphics since then have been:
- Flat shading: A technique that shades each polygon of an object based on the polygon's "normal" and the position and intensity of a light source.
- Gouraud shading: Invented by Henri Gouraud in 1971, a fast and resource-conscious technique used to simulate smoothly shaded surfaces by interpolating vertex colors across a polygon's surface.
- Texture mapping: A technique for simulating surface detail by mapping images (textures) onto polygons.
- Phong shading: Invented by Bui Tuong Phong, a smooth shading technique that approximates curved-surface lighting by interpolating the vertex normals of a polygon across the surface; the lighting model includes glossy reflection with a controlable level of gloss.
- Bump mapping: Invented by Jim Blinn, a normal-perturbation technique used to simulate bumpy or wrinkled surfaces.
- Ray Tracing: A method based on the physical principles of geometric optics that can simulate multiple reflections and transparency.
- Radiosity: a technique for global illumination that uses radiative transfer theory to simulate indirect (reflected) illumination in scenes with diffuse surfaces.
- Blobs: a technique for representing surfaces without specifing a hard boundary_representation, usually implemented as a procedural_surface like a Van-der-Vaals equipotential (in chemistry).
Related topics
Several important topics in 2D and 3D graphics include:
- Color theory
- Raster graphics
- Vector graphics
- Geometric surface representations
- including, polygons, Bézier surfaces, splines, subdivision surfaces, implicit surfaces, point-set surfaces, and NURBS
- Material properties, including BRDFs
- Image compression
- Animation
- Rendering
- Compositing
- Projection
- 3D projection
- Hidden surface determination
- Vertex shaders and pixel shaders
- Full screen effects
- Non-photorealistic rendering
Toolkits and APIs
For an application relying heavily on computer graphics, the following could be useful:
- OpenGL
- Open Inventor
- DirectX
- GKS
- Computer Graphics Metafile (CGM)
- PostScript
- X Window System
- Crystal Space
- Adobe Systems
- Pixia
- Macromedia Flash
- Macromedia Shockwave
- BRL-CAD
- SVG
- GLUT
See also
- Bresenham's line algorithm
- Computer-generated imagery
- Computer vision
- Digital image processing
- Graphics processing unit
- Graphical output devices
- List of computer graphics and descriptive geometry topics
- Utah Teapot
- Stanford Bunny
- SIGGRAPH
- ASCII art
External links
- History of Computer Graphics series of articles (http://hem.passagen.se/des/hocg/hocg_1960.htm)
- The ARTS: Episode 5 (http://www.acid.org/radio/index.html#ARTS-EP05) An in depth interview with Legalize on the subject of the History of Computer Graphics. (Available in MP3 audio format)da:Computergrafik
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