I don't know were this came from .I just pulled it out of Word but its thread related so I thought I would paste in here



As a result of what I've learned, coming from a realtime OpenGL/Direct3D background, I feel that raytracing (or other predominantly non-realtime techniques such as radiosity) will likely make some kind of appearance on future generations of graphics hardware. Optimised raytracing is amazingly fast, and handles incredibly detailed scenes at a logarithmic expense of processing power. In other words, it is far more efficient at rendering massive scenes than current techniques. While optimised raytracing is very memory intensive, RAM is relatively cheap, graphics processing power is not.

Standard realtime graphics systems in use today have a linear response to scene complexity. Because of this, Graphics Processing Units are getting immensely fast, but even with the advent of realtime Shaders, there are still many effects that cannot be achieved in realtime - some of which are achieved as part of the core algorithm of raytracing. Optimised raytracing can happily render the entire Earth from space in life-like detail, acounting for all surface detail and reflecting light off the moon - approximately the same number of rays are cast as when rendering a single low-detail teapot.

But enough hype, raytracing has many downfalls, such as massive tree structures (for optimisation) that require equally massive amounts of memory, a linear response to the number of lights in a scene, and the fact that indirect lighting isn't usually accounted for. Newer radiosity-based techniques such as the radiosity-based Global Illumination (GI) have already been implemented in realtime software (but slowly, and on very simple scenes), which does help solve the indirect lighting problem of raytracing. Within a few generations of 3D accellerators I wouldn't be surprised to see some GI, raytracing or a hybrid system appear in hardware. Until then, non-realtime raytracing is being contantly improved, and is still critical to many sectors, including the film industry, architectural firms, and other creative industries.