Ray-tracing is an old technique, based on the numerical simulation of geometric optics. Intuitively, it can be seen that light rays can be traced from a light source along their paths until they reach the observer. However, this is a very wasteful approach in computer graphics, because only a few rays coming from a given source actually arrive at the observer (if they ever do). This is why the first algorithms involving ray-tracing carried out the process in the opposite direction, as first suggested by Appel (1968): rays are traced from the observer to the objects in the scene, as shown in Fig. 10.1. The first practical use of the ray-tracing technique in computer animation was the MAGI system (Goldstein and Nagel 1971), which used the algorithm developed by Appel (1968) for solving the hidden-surface problem. Extending this method, MAGI developed the commercial CAD/CAM system SYNTHAVISION. However the most striking application of ray-tracing is the generation of high-quality images involving refraction, reflection, and shadows. The first two implementations of a ray-tracing algorithm for rendering purposes were by Kay and Greenberg (1979) and Whitted (1980).
KeywordsMotion Blur Raster Image Stochastic Sampling Pinhole Camera Model Strip Tree
Unable to display preview. Download preview PDF.