Vray fastSSS2 and Misss_fast_skin_maya

[sharktacos]

I'm trying to get my head around the Vray skin shader. I'm used to mental ray fast skin shader. Here are some questions:

1) can someone point me to some good tutorials? I did a Google search and came up empty handed.
2) Normally I would zero everything out on a shader and then turn stuff on one item at a time to see the affect. If I set everything to zero on the skin shader however still get a Lmabert gray. Same thing with the vrayMtl. What's up with that?
3) The Vray skin has diffuse, sub-surface color, and scatter color. The MR shader has

diffuse (I assume that's the same),
epidermal color, weight, and radius
subdermal color, weight, and radius
back scatter color, weight, and radius

I'm guessing that there is only one radius for the whole vray shader (scatter radius) along with the scale which would be the same as the MR algorithm control scale. I don't see any weights, but I'm guessing that this is set up more like the skin is in Modo where front and back scatter is controlled with the vray phase function. The thing is in Modo skin shaders are usually stacked so it would consist of 3 shaders layered on top of each other each with different settings to emulate the epidermal, subdermal, and backscatter layers. Here an example of that in Modo.

Really what it boils down to is me not being clear on the best workflow, since in both Modo and mental ray I would work by zeroing out everything to black and then set each attribute in isolation step by step. That does not seem to work here. The scatter color for example seems to be dependant on the sub-surface color for example.

So any tips would be welcome!

[MoonDoggie]

I've got my VRaySSS2 shader setup on an old man head that I did. It's for max, but the key was minimal use of maps and lighting. it's called "Old Man Head" I think.

[aweidenhammer]

The 3dsmax docs have the best SSS examples here:
http://www.spot3d.com/vray/help/150S...ayfastsss2.htm

This should give you a pretty good idea of how to use it. It is not as "modular" as the MR version. Also, the diffuse contribution is a "blend" to the SSS contribution. So if you have diffuse amount high, you will see very little SSS.

Also, the docs are here:
http://www.spot3d.com/vray/help/maya...ss2_params.htm

generally the subsurface color is your epidermal and subdermal coloring. The scatter color controls the internal scattering color and the amount of translucency in the object.

[sharktacos]

The 3dsmax docs have the best SSS examples here:
http://www.spot3d.com/vray/help/150S...ayfastsss2.htm

This page is indeed very helpful, thanks! There is a broken link in the Maya Vray handbook in the Examples section for VRayFastSSS2. I'm guessing it should point to this. I would be good if someone from Chaos could fix that link.

Any idea why it is not possible to zero out the VRayFastSSS2 or VrayMtl shaders to black? That is, setting all the sliders to black on these shaders does not give you a pitch black, it gives you a gray Lambert-like material. What's up with that?

Is there a way to layer these shaders in Vray in order to emulate for example the two specular components in the MR skin shader, or to have dual epidermal and subdermal components? Would VRayBlendMtl work to blend two SSS shaders? Does anyone know of any examples of someone attempting this technique (in Max I imagine since Maya may be too new)?

[vlado]

This page is indeed very helpful, thanks! There is a broken link in the Maya Vray handbook in the Examples section for VRayFastSSS2. I'm guessing it should point to this. I would be good if someone from Chaos could fix that link.

Thanks for the pointer, will fix it.

Any idea why it is not possible to zero out the VRayFastSSS2 or VrayMtl shaders to black? That is, setting all the sliders to black on these shaders does not give you a pitch black, it gives you a gray Lambert-like material. What's up with that?

Hm, this part works fine for me. Note that VRayMtl has an Opacity slot which, if set to black, will make the material perfectly transparent.

Is there a way to layer these shaders in Vray in order to emulate for example the two specular components in the MR skin shader, or to have dual epidermal and subdermal components? Would VRayBlendMtl work to blend two SSS shaders? Does anyone know of any examples of someone attempting this technique (in Max I imagine since Maya may be too new)?

You can use the VRayBlendMtl material for this; it works fine with to blend SSS shaders.

Best regards,
Vlado