Hello to everyone... Few days ago i finished my first radiosity calculator. I don''t know if my approach is good or how much good it is, but it works for now. In fact, i made it using only the general knowledge a novice, on the subject, programmer can get by reading papers on radiosity. I mean the general idea is that every point in a 3d world is an emitter and a receiver of light!!! That''s my approach. And the implementation is done using raytracing. From every lumel in the world, that has some amount of light to give, shot to every other visible lumel. The amount of light transfered from lumel to lumel is computed using form factors (this is the radiosity part!!!). I know this is not the classical matrix solution radiosity, but this is how i did it. Know, i want to know, if there is any tutorial, or detailed paper on more advanced radiosity techniques, such as hemicubes, or Monte Carlo raytraycing, for speeding up the whole process. And something i read all over the net(!!!). Is real-time radiosity possible????? I saw a course on gameversity (nice name!!!), and some papers on the subject, but no source or implementation on that. So, i must say that i''m a little suspicious on that. I mean, how much real-time, can radiosity calculations be??? Real-time means 30-60 FPS??? And then where someone can put AI, or simple animation, if the most time i spent on lighting calculations??? And in what kind of cpu, can it be real-time??? I mean there is no GPU specific stuff that can help radiosity (i think), so all the work must be done by the cpu!!! Thanks in advance... HellRaiZer

Thanks for the link.
I already read it. And despite the fact, that i had no problem with the maths (maybe a little!!!), i didn''t understood the main principles of it. So i can''t use it. And, if i remember right, it can be used for self shadowing only. It doesn''t produce shadows and other stuff. It just lights the model!!!! And if you want a demo, try playing Unreal 2. I nearly sure that it use this technique, for lighting animated models!!!

HellRaiZer

Please if you have code, the upload it. I''m very curious to see it. Btw, the demo was impressive. Good job.

HellRaiZer

Perhaps I should just add one little note: although SH lighting is currently the new hype technique, and often praised as the ultimate solution for lighting, it is in fact far from that. SH lighting research is still at the very beginning, one have to keep that in mind.

Besides it being a very interesting technique, it has a lot of nice advantages, that''s for sure: implicitly encoding light transfer functions of individual lightsources allow (unlike traditional radiosity *) a fully dynamic light environment with all the nice additions we know from global illumination: interreflections, soft shadows, colour bleeding, etc.

But that''s pretty much where the advantages stop. It has many drawbacks: the most obvious being, that it is a static model technique. It is not applicable on dynamic, moving objects. Yes, you can interpolate (and also rotate) the transfer functions, but the visual results of that are generally bad, especially if complex shadows are involved. So, this limits you to static models - just as traditional radiosity. Compared to traditional progressive refinement or Monte Carlo radiosity, spherical harmonics tend to have much worse quality. The transfer functions just can''t capture the details needed to accurately represent hard and complex shadow boundaries.

That said, research on SH lighting is advancing every day, so those limitations might eventually fade away. Especially the dynamic model issue is under heavy investigation. But with the currently available models, you should ask yourself, if an implementation is really worth it - especially if you already have a working traditional HDRI/radiosity solver. Not to say that SH lighting is bad, there are lots of interesting applications for it. But it is not the miracle solution some people think it is.

*) Note: It is also possible to encode per-vertex or even per-pixel incident-direction dependent transfer coefficients using a traditional radiosity approach. This will also allow a dynamic lightscape, similar to SH lighting, although more limited (and at a higher memory cost). But OTOH, the quality will also be much better. You decide.