OTOY Forums

Hello, I'm coming over from Lux and really loving this renderer, but I'm kind of failing at the SSS. I'm mixing a glossy material (diffuse, spec, and bump maps) with scattering medium connected to specular material. It seems I get very negligible results if any...am I doing something wrong?

I set the scattering material - absorption has a flesh color I put in as an RGBspectrum and the scattering is set to 1. The scale is all the way over to 1 as the more to the left it goes the figure color turns black. The specular material has been left alone except reflection and transmission being set to 1. The scattering material is connected to the specular via the medium node.

The Glossy material and the specular/scattering material are then connected to the mix material and I find that I have to bring the mix almost up to 1 to get anything like the brightness of the skin I want.....but I am assuming that is almost like 1 equals almost totally gloss material alone without the SSS.

The figure comes out of DAZ studio 3 and scaled to 39.3701 as per the manual, but someone suggested setting the scale to 1% in another post. I've tried both with similar results....any ideas?

I will say one thing.....having the speed of my GTX580 makes updating materials so much easier vs Lux where it could take days to get similar amounts of S/px! It is a very user friendly renderer, and took only a couple days to get very comfortable with the workflow.....well worth the $150 US I spent.

Anybody?

Subsurface scattering in specular materials is noisy at the moment, and it doesn't work with the sunsky model. It should work fine if you use big enough emitters, or an environment map. For skin you should test if using a diffuse material with transmission is adequate.

Can you post a rendered image so we can see what it looks like now?

--
Roeland

If you look at the tests people have done in the gallery section, you'll see that the SSS effect is very subtle, almost unseen, when the key light is frontal. To see better the effect try to use side or back light.

If it is any consolation, I also haven't been able to rig useful SSS for skin. I always get a lot of white-cyan noise and render times duplicate or triplicate (but this later is probably to be expected).

Thanks Roeland, I will put a pic together with a light behind the subject to show no SSS. Question regarding using the diffuse material with a transmission, that would be mixed with the glossy material so it would just replace the specular side of the mix?

Matej you are absolutely correct as the SSS is a very subtle. I am thinking that a grayscale map of some sort would be used to create more SSS in certain areas like the ears, fingers and toes. Well, at least I know I'm not missing anything if your not getting the results either.

I'm coming over from DAZ 4 to Lux and I have to say Octane is a real great choice on my part. I am really looking forward to the future with this software.

@boeing727223, check the wip gallery section, where users posted a lot of tests. There you can find hints on how to use SSS for various materials. Also here is a complete explanation of parameters by roeland, in case you missed it.

Thanks Matej, Roelands explaination has been my guide, but it looks like he is maybe using a 2.55a. Version 2.55b I don't find Transmission Texture...I may have overlooked it...what I did find is Texture Emission...is that the same thing? I don't see how that is possible, but I can't find Transmission Texture...

Well, a "transmission texture" is any texture node plugged into the transmission parameter of diffuse or specular shader. In the case of specular shader the transmission is already set right for SSS effect, but in case of diffuse shader you must plug a non-zero texture node into the transmission slot, if you want to use SSS with it.

Gotcha, but I also noticed that the diffuse material is missing the transmission parameter for 2.55b......hmmm