InfernalDarkness:
"...you'll find that radiosity is indeed just like real light."

Humbug.

Having already read up on radiosity, and on global illumination mechanisms, I am fully aware that they are all very unlike real light. If you believe otherwise then you are ignorant of the details of these processes; or of how real light works (or both).

Photon mapping is the most like real light to the extent that the simulation does at least involve some virtual light starting out from a designated source and being followed (to some degree) as it interacts with a scene in a way analogous to actual light behaviour. But this is only one part of the process and very limited in scope. There has to be a statistical estimation made to compensate for that limitation. And the resultant "photon map" has to be combined (via another estimation) with normal ray-traced direct illumination in order to simulate any indirect illumination. The combination involves what you call "data rays" being sent outwards via the ray-trace renderer in order to cross reference with the photon map. Like real light? I don't think so.

Radiosity algorithms also simulate the interaction of light between surfaces, but they work "back" from the (arbitrarily subdivided) surfaces, not "out" from a light source. The algorithms involve imaginary, compromise constructs such as the "Nusselt Analog" and the "hemicube" that also have no counterpart in the physics of real light.

All 3D graphics processes are simulations and analogies. Even those that use algorithms that take into account some of the characteristics of real light still work in unrealistic ways to achieve an illusion of reality. There is no spoon.

If the pictorial results from using Bryce True Ambience (and other "quicky" workarounds of Distributed Ray Tracing that might save from "having to program anything") can be as realistic as those produced by other rendering processes, then that's fine with me. That is the context in which I stated that True Ambience is as close to radiosity as makes no difference.

I really couldn't care less if these entirely mathematical "rays" work forwards, backwards or sideways.