I’ve been required to do skin shaders in V-Ray from time to time at work and I usually like to start with the data provided by Digital Human League for the Wikihuman Project as a reference. You can find the available data here: http://gl.ict.usc.edu/Research/DigitalEmily2/. It’s a set of textures captured at the ICT Lightstage of an actress named Emily and the data set is referred to as Digital Emily. For Maya users there’s a Maya scene included, prepared with lights and shaders just ready to render. However, if you’re not just using it as it is and perhaps want to use the shaders as a starting point for your own project the setup is not ideal as it relies on plugin materials instead of the regular materials in V-Ray. For example the SSS shader looks like this:
I would much rather have a VRayFastSSS2 material instead and a VRayMtl for the specular components. It’s fairly straight forward to convert these plugin materials to regular materials. I’m happy to share my Maya scene with my already converted shader setup. Just write a comment in the section below. This shader setup is a pixel perfect match with the plugin material setup and the results looks like this:
I think the results are quite nice, but there’s some parts of the SSS I don’t like. The glowing parts around the nose for example. And the shader setup is quite complex with four different materials blended together. The node tree looks like this:
With the release of AlSurface Shader in V-Ray there’s a possibility to get even better result within one single shader using the same textures. Here’s a blog post from Digital Human League about this topic: http://www.wikihuman.org/index.php/off-topic/the-alsurface-shader-on-the-wikihuman-data/. Here they use the Digital Mike data set, but that’s not publicly available as far as I know. They describe briefly how to use the AlSurface shader instead but doesn’t go into detail. It’s fairly straight forward, but there are some potential pitfalls. First of all you need to invert the single scatter map. You can either use an external program, like Nuke, but the easiest way is to use a Reverse node in Maya. Another thing that needs to be inverted is the Reflection Roughness values compared to the Glossiness values in the VrayMtl. For example 0.2 insead of 0.8 and so on. Here’s the settings I ended up with:
Once again, as I’ve already done a conversion and have a prepared Maya scene I’m always happy to share it if someone’s interested. Here’s the result using the AlSurface Shader.
It took a bit longer to render but I like the result more. I think the SSS feels more realistic now and have less of the glowing effect from the other setup.