CompuServe Messages

Robert, modelling is what we call the design of three-dimensional objects. The tool used for this is a modeller, which can be interactive or script-based. The so modelled objects will be put to action in staging, which is the placement of objects, a camera and light sources like actors on a stage. This setup will now be rendered, meaning you have the computer simulate the picture a human eye or a photo camera would see if it were in that virtual environ- ment. ray-tracing is just one of many methods of rendering a picture. It was the first to be developed. It is fairly easy to program and produces extremely realistic output. Ray-tracing is however painfully slow. What it does is follow the rays of light from the light sources into the eye, reflecting and refracting on the objects inbetween. In fact, it does this backwards. Other rendering methods use approximations to get around calculating millions of light rays. They include phong and gouraud shading algorithms. Modern renderers use one of these fast methods plus they apply ray-tracing selectively in those parts of the picture that require it. Hope this answers your questions. Tom / Amiga Imagineer from Switzerland with AutoPilot engaged