CAN YOU EXPLAIN YOUR PROCESS FOR REALISTIC SKIN?

Skin can seem daunting and difficult to render and the intricacies around how light scatters makes the whole subject of subsurface scattering very confusing, but when you get a handle on it, it’s actually really simple.

Generally I find that having a bit of an understanding of the physics of how light works gives me a logical framework to start experimenting from. Key to helping me understand the basics of skin is understanding how blue light will generally scatter more easily than red light, with Tyndall and Rayleigh scattering.

So if we set our scattering colour to a light blue, then blue light will scatter back at us and the remaining light that passes through and out the other side is a warm orange, which just so happens to be what we see with skin! You might think it is the red of blood that makes skin glow red. Well, yes, but only past a certain depth.

To achieve this effect we generally need to mix at least two scattering shaders: one for the surface scattering that will give us our general skin colour, and one for a deeper red scattering that is about half as dense.

To add the general skin colour I remove some of the blue tone from the albedo map and then use this to control light transmission. This compensates for the blue light that is scattered and also helps the shadows to be a bit warmer. I then use a solid red for transmission on the deeper shader and twist some dials – and boom, you have skin. This mostly follows the skin shaders that Tony Reynolds has set up for use in Octane.

That’s the basics of the scattering, but also the key to realistic skin is having decent micro details, for which I highly recommend Texturing XYZ. It has easy, hasslefree displacement and albedo maps.

I hope this is of some help. I guess one main point is that with a PBR workflow it really helps to understand some of the physics of light so you are not just twisting random dials and waiting to see what happens. I recommend reading up on the Tyndall effect and Rayleigh scattering.