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In this article:
- What is computer graphics
- 2D and 3D graphics
- Shading and Rendering
What is Computer Graphics
The use of computers to generate images artificially is called computer graphics. The term computer graphics was coined by William Fetter in 1960 while working at Boeing. The Sketchpad, developed in 1963 by Ivan Sutherland was a major development in the field of computer graphics.
Computer graphics, as a field, involves various activities such as 3D Rendering, animation, special effects, image editing and modeling etc. The first use of computer graphics in order to show their power was in FutureWorld (1976) that showed an animated human face and hand.
2D and 3D graphics
A real revolution came in the field of computer graphics when Cathode Ray Tubes or CRTs were first used in the field. The area of computer graphics was originally comprised of entirely 2D (short for two-dimensional) graphics. These maybe of either of the two types, that is, vector or raster.
The typical feature of vector graphics is that they store very accurate geometric data and other information such as location of points etc. They also keep a record of the color and thickness of images. Originally, vector graphics were displayed on monochrome CRTs.
On the other hand, raster graphics are comprised of a 2-dimensional grid of pixels where each pixel is given a certain value regarding its brightness and color etc. The number of rows and columns in a raster image determine its resolution. In today’s computing world, both of these 2D formats are combined (such as in PDF files and Flash animations).
3D graphics, on the other hand, are of more recent origin and 3D polygons form the base of all 3D graphics that exist. 3D graphics store single 3D coordinates and lines that connect those points with each other, the resulting ‘face’ of the polygon and a series of faces that makes the 3D polygon.
Shading and Rendering
Shading in computer graphics makes use of computer simulation to determine how a polygon is going to appear when it is illuminated by an artificial source of light. On the other hand, image-based rendering makes use of various images taken from different points of view and combining them to give it a 3D look. There are various techniques in image-based rendering. They are explained below:
- Flat shading
This is a technique where each polygon is shaded depending on the position and intensity of the light source.
- Gouraud shading
A technique invented by Henri Gouraud in 1971, this reproduce shaded surfaces that are smooth with the help of vertex colors that are interpolated on a polygon’s surface.
- Texture mapping
This is a popular technique which ‘maps’ or textures images on polygons thus giving them the look of a particular type of surface.
- Phong shading
This technique was developed by Bui Tuong Phong and it interpolates the vertex ‘normals’ of a polygon to find the approximate effect of lighting on a curved surface. Using this technique, one can also control the glossy reflection which may result from shiny surfaces being enlightened.
- Bump mapping
This technique is used to reproduce bumpy or wrinkled surfaces through perturbation. It was developed by Jim Blinn.
- Normal mapping
This is an advanced form of the bump mapping technique and it helps simulate bumps and other such complicated details in an easier way. It makes use of low polygon models to achieve this.
- Ray tracing
Ray tracing is a technique which uses the physical principles that govern geometric optics to its benefit. It is used to simulate transparency of objects and so also, multiple reflections at a time.
- Radiosity
This technique is used to simulate illumination that is a result of the light being reflected from some other surface by making use of radiative transfer theory.
- Blobs
As against other conventional techniques, blobs are a unique method of surface representation in the sense that there is no hard boundary for the graphical images that emulate a surface.
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