What makes these discussions of rendering techniques fascinating and frustrating in equal measure are the multiple definitions, often proprietry, floating around for the terms used.

"Global Illumination" is a good example.
e-on, for their Vue program,** **appears to regard it as the use of the sky dome as a big area light providing an all round illumination for "outdoor" scenes. Mental Images, for their MentalRay renderer, seem to regard it as a combination of Photon Mapping and Final Gather. End users enjoy an even wider variety of interpretations.

My understanding of "Global Illumination" is that it is a combination of render processes that together simulate all the light interactions seen in the real world. As such, radiosity, ray-tracing and photon mapping (for example) are not separate from Global Illumination; rather they are subsets of Global Illumination. This is the description I have seen on the web in articles that are not linked to commercial 3D programs. It is usefully summarised in this WikiPedia piece.

I point this out because I think I disagree with a lot of what Rayraz is saying, but can't be totally sure because I don't think we share a common point of reference. I certainly disagree with this: "TA just uses the rays that are already there from the direct illumination..."

Anyways, the discussion may be totally irrelevant. For all most of us know TA might have been completely removed from Bryce6. Only the beta testers here know that. They're probably giggling as we type. Bastards. ;-)