Transparanecy with vrayfast sss2

[michae]

Hi I am currently creating a shader for a semi transparent sub surface material. I am using the vray fast ss2 and I have the single scatter mode set to ray traced refractive and im having trouble controlling the transparency and color via the sub surface/scatter colors. When changing the sub surface color or scatter color my colors bug out and change to something completely opposite same with the transparency . I am not sure If I am using the shader incorrectly or I am running into a bug but any help towards workflows techniques with this shader would be greatly appreciate.

Thanks ,

Michael

[vlado]

There are some examples and explanations here: http://www.spot3d.com/vray/help/150S...stsss2.htm#ex8 I hope they are useful.

Best regards,
Vlado

[michae]

Thanks for the reply but I have gone over those docs for both max and maya and Im not getting much luck. The color and settings for what they describe should do doesnt exatcly match up. Are there known bugs with this shader?

Michael

[LarsSonparsson]

Same thing happend to me yesterday.
Tried to create deep warm coloured liquid, but the result was
totally opposite blueish. It looked that very low valued colours worked more like a filter.

Well, this was in max 2010 sp5, so not sure is it a same problem.

-LarsSon

[vlado]

Are there known bugs with this shader?

Nope; seems to work as it is supposed to (although obviously perhaps not quite as you expect).

Best regards,
Vlado

[aweidenhammer]

To be a bit more verbose... You can have very opposite colors refract through your object, when your subsurface and scatter color aren't similar. For best results, I'd suggest keeping them similar. The link Vlado posted has some very specific color examples at the bottom (the colored spheres). They illustrate the problem you're having. You are most likely using a subsurface color that isn't very saturated, and a neutral scatter color. You'll get more controllable results by either using more saturated colors, or keeping the scatter and subsurface colors in the same hue family... unless you're going for a very specific effect. If you are looking to achieve a very specific effect, let me know, and I'll see if I can make it work. I just did a nice transparent refractive SSS material.

[michae]

Thanks for the reply aweidenhammer,

From what ive been working on I have been keeping them in relatively close hue's. But it seems random when i start adjust the scatter colors values that my subsurface will randomly go transparent with very opposite color that are no where in my shader. Right now Ive been faking ss with a refractive mtl shader which is giving a nice result but I'm not sure if its the most effective. The material I am going for is a gummy/fruit roll up/gusher material.

[aweidenhammer]

It is a bit tricky, but a general rule would be to keep your colors a bit less saturated. In particular, the subsurface color. If I want to add a bit of saturation in I bring in a bit of diffuse with high saturation. OR, you can use a standard material to create a similar "gummi" material. I included both in the scene file you can find here:
www.motr.net/vray
sssRefractive.mb

I'm relying on an HDRI to light the scene, so You'll have to hook up your own to the domelight. Ideally, you rotate until some bright part of the hdri is behind the object, to see refractivity.