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I am traying to render a character in blender. I am using Principled BSDF. As a subsurface emthod I am using Random walk, since it gives more realistic results. Whole face is fine except eyelids. They become blue. I guess it is due to thin geometry. Any Ideas How to solve the problem?

enter image description here

--Edited--

Here is shader graph: enter image description here

As Base color I use orangish colored texture. SubsurfaceFactor is a gray scale map. I used original Subsurface Radius values (1.0, 0.2, 0.1) multiplied by black color to steer the radius easily.

I get this thin geometry using boolean modifier. I subtracted eye shape from teh face shape to prevent flesh appearing in cornea.

Another problem are those strange speckles in shaded area? Does anybody know what cause them? I had same problem when I worked with Arnold Render, so probably something's wrong with my setup.

enter image description here

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  • $\begingroup$ Could you tell a bit more about your shader setup and maybe show the nodetree? What's your subsurf radius vector? $\endgroup$ – Carlo May 13 '18 at 15:10
  • $\begingroup$ I am experimenting the same thing (the blue color on thin surface). I think it happens when the thickness is under the blue color radius (or the color -red green or blue- which has the min radius). Maybe we could play with inverted ao to reduce the sss scale on these thin surface (Not tried yet) $\endgroup$ – Charles HETIER Jan 7 at 23:13
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My 2 cents tweak to avoid blue patch on thin surface: enter image description here

I adjusted the distance of the ambiance occlusion to be small enough to be near to zero on thin surfaces. I disabled "only local" to prevent collisions with external objects to also add blue color around the collision surface.

Here is how my ao values look like:

enter image description here

As a result, from this: enter image description here

... to no more makeup: enter image description here

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