How to use Subsurface Scattering in Principled BSDF

Question

The Subsurface Scattering in Principled BSDF is a bit confusing:

• Where can I find some recommended presets (like in other software)?
• What is the main difference between SSS Color and Radius?
• (Technical papers don't help very much, I'm not an engineer)

Answer 1

Subsurface slider

• Use it to scale Scattering depth down to realistic values
• When set to 0, scattering is disabled

Values of around 0.01 are normal, since you're usually scaling from meters to milimeters.

Subsurface Color

• Primary color. Visible on opaque parts and in shadows.
• Generally, use the same image/color you used for Base color to avoid color mixing

Subsurface Radius aka Scatter Color

• Secondary color. Visible on edges and translucent parts (like ears).
• Connect an RGB node or a texture. This is a good place for a subdermal map.
• The RGB values here represent how deep light penetrates in meters (!).

Correct radius is important to get right. Scale it down using the Subsurface slider.

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Example of SSS setup

Stanford Dragon, 15 centimeters
Marble values set from reference chart below
Subsurface slider set to 0.01, to match SSS depth of marble (~8.5 milimeters)

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Recommended values chart

Size matters: For SSS to work correctly, your model needs to be in real world scale.

_{^{Source chart from Pixar. Original paper here}}.

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Sources
_{^{Link - Henrik Wann Jensen, Stephen R. Marschner, Marc Levoy and Pat Hanrahan: "A Practical Model for Subsurface Light Transport". SIGGRAPH'2001.
An Introduction To Real-Time Subsurface Scattering, Stanford Dragon - Stanford University Computer Graphics Laboratory, Subsurface - Arnold Renderer, Subsurface - Substance Painter, Subsurface - Renderman}}