Author Topic: SSS Material  (Read 5753 times)

Where can i find info on making material using MDL and producing Sub Surface Scattering materials as shown on this vid

 https://www.youtube.com/watch?v=V8YPDaJWpFc

Try to follow from his graph, though cannot clearly see which nodes are used.

Thanks for pointing this video out. It appears he has a 'material volume' plugged into the 'volume (material volume)' slot on the main material node. There is a float value for the IOR plugged into it as well. There are 'volume absorbtion' and 'volume scattering' nodes plugged into the 'material volume' node (the one with a purple vdf node plug). The volume absorption has a color that you should set to the subsurf color you are looking for (red?). Having tried this setup, it seems you need to make sure that you have the ggx bsdf (that is plugged into the material surface) mode set to 'scatter reflect transmit' rather than the default of just 'reflect'

Hi madgamer2000,

Thanks for your reply and suggestions, i`m still not able to get the correct results.
I still don`t know what are the two nodes on the left of (microfacet ggx smith bsdf).

I have attached the file and view of my setup.
Your help is greatly appreciated.

Also in that video they show the results using the Open gl shader.
My render program does not support the iray shadder only open GL.
I dont seem to be able to replicate thier procedure.

The nodes to the left of the ggx shader are the roughness value (just a float value) and a multiplication node it is plugged into, multiplying it by itself to get roughness behavior that uses values that translate better to the ones you are used to working with in substance designer/painter. They explain it a bit in the mdl intro tutorial that they put on the official allegorithmic youtube channel. For the IOR, I notice you have a node called 'abbe number' plugged in. That may work, but a simple float value with a number around 1.5 will work fine and is what I used. As for the iray to open gl conversion, I'm not really sure what to tell you on that. Any real time (directX/openGL) subsurface scattering approach (currently) is going to use a lot of approximation and work very differently from how it does in a ray traced solution like iray, as you don't have time to compute the ray traces required to get real refraction. In the youtube comments of the existing mdl tutorials, allegorithmic have said they will be doing more tutorials shortly covering stuff like this (SSS etc), so maybe they will address that and be able to help you.
Last Edit: September 02, 2016, 12:48:01 am