Hello all, I am trying to basically get realistic leaves. These leaves are billboards. I have tried several techniques - normal N.L diffuse lighting, using normal maps, etc. They still do not have a translucent effect that they have in real life. I think this is called Subsurface Scattering - and from what I have read it is a costly process - to costly to perform on leaves. I was wondering if anyone had any ideas on how to possibly fake SSS? Or to get realistic leaves ;) Thanks, Adoado.

In the DX9 SKD there is a sample called LocalDeformablePRT; I think the technique used there would work great with leaves.
A screenshot:

For things like foliage I think a fast approximation is needed.

If you are casting shadows from your tree onto itself then things are easy.. just make the faces pointing away from the sun brighter if they are NOT shadowed.

Otherwise, you need some kind of reverse lighitng term...you can us ea mask texture to control scattering brightness.. I thin it s amatter of fiddling around till somehtinglooks good.

Even in Crysis the foliage doesnt have perfect SSS

Subsurface scattering is light rays bouncing around inside the object. A leaf is mostly 2D and I don't think its necessary to simulate this happening at the molecular level to make it look good. Basically you can just simulate the light behind the leaf shining through and illuminating it a little bit. The only visible effect that SSS has is to make that light look more green. Therefore, I think that a good fast approximation would be to use an opacity map to show which areas of the leaf can let light through (eg, not the veins)...and then you can add some ambient green color to the areas that have less opacity.

actually on second thought...it ought to look good enough with just bump, diffuse and specular maps...i think the trick is just in getting good maps.

[Edited by - yahastu on October 29, 2007 12:47:30 PM]

Kambiz, thanks but from the looks of that example I do not need such accuracy. Like Matt and Yahastu said I think I need some type of fast approximation. Thanks, though ;)

Quote:
Basically you can just simulate the light behind the leaf shining through and illuminating it a little bit.

This sounds like an awesome idea to look into - but how would I do this - sorry, I am still a beginner at HLSL..

Somehow make the spot directly in the path of the light brighter?

Thanks,
Adoado