Maxwell > faking SSS
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In response to a thread on the Maxwell forums regarding tests to achieve Sub Surface Scattering (SSS) materials for vegetation I decided to do some testing of my own in an attempt to fake it.
The problem till now has been that the use of simple transparency to to single plane leaves produces rather weird results as the single plane geometry produces refraction and with no thickness the effect goes spastic!!!
Using SSS has the drawback that all meshes must have thickness. The other issue is that the material is also then homogenious and the leaf structure (the skeleton) transmits the same amount of light as the surrounding leaf area and then this skeleton is visually lost when light passes through the leaf volume.
My solution which looks to be working applies a B & W noise map to 2 additional BSDF layers each map is the inverse of each other so to in effect pass light through tiny holes (white areas clipped) over the whole single plane. Obviously then the leaf skeleton can be left black on the map and the effect there is to ensure no light passes through these areas.
The results so far seem promising though I have obviously over weighted the transparency layers for this quick test.
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sounds pretty advanced, the stuff you are producing there (even if I can barely see the effect you are trying to create - may be my badly calibrated monitor though
)and now I fully understand why you prefer maxwell's external material management to indigo's "all saved in SketchUp" approach. to set up this multilayered material in in indigo would be near impossible.
Richard, I am truely impressed how detailed your knowledge of material-compositing is.
I would love to see some more of your tests! -
@plot-paris said:
sounds pretty advanced, the stuff you are producing there (even if I can barely see the effect you are trying to create - may be my badly calibrated monitor though
)and now I fully understand why you prefer maxwell's external material management to indigo's "all saved in SketchUp" approach. to set up this multilayered material in in indigo would be near impossible.
Richard, I am truely impressed how detailed your knowledge of material-compositing is.
I would love to see some more of your tests!Thanks plot (again!!)
Mate I'm not so good with complex materials though have some idea how to use the editor long hand to get the result I'm after.
Yes regarding Indigo's approach! This material has 4 layers to achieve the effect I'm after (the one you can't see!!;) );
Layer 1. Colour Map / Clip Map 1 / Bump Map - Diffuse.
Layer 2. Colour Map / Clip Map 1 / Bump Map - Reflective.
Layer 3. Colour Map / Clip Map 2 / Bump Map - Reflectance.
Layer 4. Colour Map / Clip Map 3 / Bump Map - Reflectance.All said if Maxwell wasn't an unbiased Physically based renderer then nearly all of this could be done via one simple layer. So its a bit of a catch 22 - you can create amazing materials though sometimes like here you need to go to a lot of trouble to create alternatives to produce an otherwise rather simple effect.
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