THREE-DIMENSIONAL IMAGES

With the growing sophistication of computer equipment, the focus of computer graphics in the 1980s moved from the rendition of two-dimensional (2D) images to three-dimensional (3D) ones. The demands of a more complex image rendition meant that a lot more information now had to be stored on the computer. As well as rendering simple flat surfaces, three-dimensional objects require information on shading and other more subtle effects.
The basic concept that underpins all modern computer graphics is the three-dimensional polygon (a geometrical plane figure with three or more straight sides). Images are based on collections of polygons and this means that computer graphics software has to store the coordinates that define each of the polygons that comprise the 3D representation. The points, lines, and surfaces that define the polygons may be drawn or derived from measurements (for example, of a moving object or person).
The software that has been developed to render modern computer graphics does much more than simply store geometric information. The realistic images that people now expect to see require a lot more than the assembly of a massive collection of polygons into recognizable shapes. They also require techniques for shading, texturing, and rasterization of the images. The last of these, rasterization, involves the conversion of a vector-defined image into a series of pixels that can be rendered as a 3D image on a video display. Texturing is concerned with how surfaces look after being shaded, depending on the shading method, and how the image is interpreted during shading.