Mental Ray's Fast Subsurface Scattering Shader And Gi

[riskbreaker]

Does anyone know if it's possible to use Mental Ray's fast simple subsurface-scattering shader and have GI work with it? Right now I'm trying to do it and for some reason the map visualizer for GI won't let objects that have that material applied bounce photons (hence no GI is applied to them).

If this is the case, anyone have any good alternatives to skin shading that will work well with GI?

Thanks!

[joojaa]

use physical sss.

You do understand thet fast sss is afake with capital F it asumes you dont rebounce light all that much, otherwise youd get a O(n^2) against O(nlog(n)) computation now offcourse gi itself is a O(nlogn) operation or possibly so the rersult woudl be a O(n^2*n2log(n2))operation, so quickly calculating you d push a magnitude one miunte render into 0.5-20 hour render its hard toc claculate exatchtu because teh ns are independet variables tough.

However theres a faster track wich is to do tis all by photon simulation but you need hellofalot of photons.

HOWEVER what i do suggest you dioo is make a phpotonic material for teh fast asss adnthen teh photons would contribute normaly but not sss totaly right but do a pseudogoodjob

Anyway turning all goodies on is performance scuicide.

[masternull]

All the mental ray shaders do not have the built in photon shader, the maya shader do have it.

so when you use mental ray shader you have to connect a photon shader manualy in the shaderSG in the mentalray section > photon material slot.

then you edit the photon attribute to match the color,transparency, etc of your shader.

I hope this answers your question

[riskbreaker]

Thanks guys... I think I am on the right track. I connected a 'mib_photon_basic' to the 'Photon Shader' section in the SG node. The object is now receiving photons (I can see them in the visualizer)... however, in the render I can't see any noticable difference. I'm sure the photons are bright enough in the render because I can see the white circles hitting everything that has a Maya shader applied. The stupid MR shader won't show those circles though. Am I missing something? Any ideas? Better yet any samples of someone else trying to do this anywhere? I can't find any samples of GI mixed with Mental Ray shaders anywhere on the net.

[joojaa]

Yes the fast sss subsurface part wont react to those photons, this is kindof the idea of the whole shader. Again the other solution is to meka the entire sss with photons but itd be a magnitude or 3 slower.