Radiosity Questions

Hi folks,
I tried a hand at using radiosity with a simple scene and it worked like a charm. Then being bold as I am, I loaded my 350z model which is made of a bunch of meshes and splines. Some elements of the scene have more than one material. I let the solver run to completion. At the end of it when I clicked Replace Meshes, Blender complained that maximum number of material indices reached. Now some parts of the model did not retain their original materials at all. Is there a way to apply the radiosity solution to complex scenes without this material index limit of 16?

One more question, if I have sub-surf on for some meshes which aren’t converted, does radiosity use the control mesh or the final mesh?

you’re obviously using the viewport-radiosity-feature. it converts for the final result all meshes into one, hence your problem with material indeces. apart from that, it ignores sub-d meshes and uses only the base mesh for calculation. if you want to use the sub-d mesh, you’ll have to convert it using ALT+C.

to avoid those problems you should use the regular renderer with radiosity turned on, or yafray. using the internal renderer you should pay attention to the polygon count of your objects - they are NOT subdivided during render process, but the radiosity solution still assigns the solution to vertices. i.e., for accurate solutions you’ll need high poly counts.

yafray has none of these limitations, but is tricky when it comes to setting up lights - they appear much less powerful, so you’ll have to push their energy settings in order to achieve good results.

have fun


kind of, you can’t apply it to your scene
[well, simply setting the materials after blender complains of the 16 material limit back to what they should be would work but would be a pain]

you could however do the radiosity calc at render time, and not have to worry about the 16 material limit at all

press radio for your materials you want in the calc, and turn on radio in the render buttons.

if you liked your previous radiosity settings it should turn out similar
[except it will use a subdivided mesh, so you may need a higher hemirez, and you probably should consider setting a higher convergence value or setting a number of iterations because after some point, the iteration don’t make much of a difference except for making your render take much longer]

only if you do the radiosity calc at render time

Cool. I was hoping it could be pre-calculated; then I could render any view. I’ll try the radiosity at render time.

OK that worked but it didn’t produce correct results for transparency and some areas fo the model were black. How do I control the radiosity render? I want to control how long the solver runs before terminating? Is the same way you do it from the Material buttons window?

try yafray - you have a lot more options for tweaking quality vs. speed. try the latest bf-blender build, it comes with yafray as a plugin, i.e. you see the rendering in progress!

Yafray is a raytracer, right? I haven’t looked at it yet. I tried radiosity for GI. Yafray might provide a better render with HDR images as well.