i was looking over a pdf file i found a while back on hl2 and found a page talking about radiosity mapping. i know how it works but i just need to know how to implement it. the way their radiosity mapping works is they bake the environment's global illumination into simple bitmaps or jpegs or whatever format you want. my question is how do you take these colored lightmaps and have them effect your unlit texture to make them look like they have global illumination applied?

simply by blending them together. You can either do this in an offline stage and combine the two textures together with a certain blending equation such as:

NewVal = LightMapVal * TextureVal

If your lightmap has values 0 - 1 where 1 is fully white and 0 black (assume grey scale lightmap) then the brightest parts of the texture will retain their original colour, the darkest will be black.

This could also be done in game if you wanted, multi texturing each frame.

i found the article and i figured out my problem.
pages 20+ are about radiosity and specular mapping and other mapping in hl2 http://www2.ati.com/developer/gdc/D3DTutorial10_Half-Life2_Shading.pdf

i have another question for you 3d modelers and animators out there. (y waste a good post?) do any of you know of a good renderer that will bake global illumination values into a texture map? i thought mental ray would do it but apparently it doesnt. i have xsi, maya, and 3ds max 6 if that makes a difference for certain renderers. price is not a problem... my work is paying for it lol.

I'll do some work for you if I can get 3DS-max out of it :)

If I don't know how to do it... I can learn ;)

What format do you have these "global illumination values" stored in? At the very least they each have a 3d location, an intensity, & a color.

What is the environment exactly? a hl2 level? some model of your own? Some terrain?

the problem is i dont have any values stored right now. im trying to find a renderer that will store the values in a colored lightmap (jpg). i dont have any saved maps. all i have done is made some small rooms with 2 or 3 boxes in it and rendered it using mental ray.

Quote: Original post by adam17
i have another question for you 3d modelers and animators out there. (y waste a good post?) do any of you know of a good renderer that will bake global illumination values into a texture map? i thought mental ray would do it but apparently it doesnt. i have xsi, maya, and 3ds max 6 if that makes a difference for certain renderers. price is not a problem... my work is paying for it lol.

Most modelers can, ligtwave can do it, so can maya.
In maya 6 its under rendering->lighting/shading->batch bake.
Unfortunatly i havn't tested it that mutch.

crap, so adam... sounds like you might be able to do it without my help... I'd still appreciate 3ds-max ;) lol

unfortunatly i HAVE maya but i dont know how to use it very well. ive looked for tutorials around the web for getting mental ray running global illumination but i cant find one for maya 6.
if anyone knows what to do for 3d studio or even a plugin please let me know.

to use global ilumination in maya just turn it on under the rendering menu.
Allso make shure that every light you want to be affecting global ilumination(without using final gather) must emit photons.
just select the light source and under mentalray in that menu you find caustics and global illumination.

It took me about 10 minutes to figure out how to do it.