computer graphics - 3D, Shading, Image-Based Rendering

The use of computers to display information in graphical or pictorial form, usually on a visual display unit (VDU), a printer, or a plotter. Computer graphics are now used in an increasing number of applications, ranging from the manipulation of highly detailed engineering drawings to computer games, from high definition views in aircraft simulators to automatic production of animated film, even indeed as an art form in its own right. Computer graphics can make very heavy demands on computing power, and many of the faster computers have been designed with graphics very much in mind.

This article is about computer graphics in general. For the ACM SIGGRAPH journal, see Computer Graphics (Publication). It has been suggested that CG artwork be merged into this article or section. The first major advance in computer graphics was the development of 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 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 (1968), which attempted to show how computers would be much more graphical in the future.

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.

3D

With the birth of workstation computers (like LISP machines, paintbox computers and Silicon Graphics workstations) came 3D computer graphics, based on vector graphics. Instead of the computer storing information about points, lines, and curves on a 2-dimensional plane, the computer stores the location of points, lines, and, typically, faces (to construct a polygon) in 3-dimensional space.

3-dimensional polygons are the lifeblood of virtually all 3D computer graphics. As a result, most 3D graphics engines are based around storing points (single 3-dimensional coordinates), lines that connect those points together, faces defined by the lines, and then a sequence of faces to create 3D polygons.

Modern-day computer graphics software goes far beyond just the simple storage of polygons in computer memory. Today's graphics are not only the product of massive collections of polygons into recognizable shapes, but they also result from techniques in shading, texturing, and rasterization.

Shading

Shading in hand-drawn graphics can be done in several ways;

In the context of 3D computer graphics, the process of shading involves the computer simulating (or, more accurately, calculating) how the faces of a polygon will look when illuminated by a virtual light source.

Image-Based Rendering

Computer graphics is all about obtaining 2D images from 3D models. Simulating the real 3D world scene using Computer Graphics is difficult, because obtaining accurate 3D geometry of the world is difficult.

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. 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;

Textures add a new degree of customization as to how faces and polygons will ultimately look after being shaded, depending on the shading method, and how the image is interpreted during shading. APIs

For an application relying heavily on computer graphics, the following could be useful:

Adobe Flash Adobe Systems AmanithVG Autodesk Blender3d BRL-CAD Cairo (graphics) Computer Graphics Metafile (CGM) Crystal Space Power Render DirectX GLUT Graphical Kernel System (GKS) Macromedia Shockwave Open Inventor OpenGL Pixia PostScript Renderman Scalable Vector Graphics (SVG) svgalib X Window System

Miscellaneous

Digital geometry (e.g., Bresenham's line algorithm) Computer-generated imagery Digital image editing Timeline of CGI in films Computer vision Image processing Graphics processing unit POV-ray Graphical output devices List of computer graphics and descriptive geometry topics Utah Teapot Stanford Bunny SIGGRAPH ASCII art