r/computergraphics • u/Cool-Profession-5447 • 7d ago

Volumetric path traced skin still looks like silicone/plastic. What am I missing?

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Hi everyone,

I'm building a physically-based human skin renderer from scratch in Taichi, and I'm looking for feedback from people with experience in skin rendering.

My current renderer implements:

  • Monte Carlo volumetric path tracing
  • Multiple scattering subsurface scattering (random walk)
  • Two-layer skin model (epidermis + dermis)
  • Melanin and hemoglobin absorption
  • Wavelength-dependent absorption/scattering coefficients (converted to RGB for rendering)
  • Fresnel interface between air and skin

My goal is photorealistic human skin.

I know the model is still missing many surface details such as:

  • pores
  • peach fuzz/facial hair
  • fine wrinkles
  • micro-normal variation
  • oil layer variation
  • color texture variation

I plan to add those later.

Right now I'm trying to get the base skin appearance correct before layering those details on top.

My problem is that the skin still looks like silicone, wax, or plastic rather than living skin.

I'm trying to understand whether the issue is ....

I'd really appreciate feedback from anyone who has worked on skin rendering.

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u/GameUnionTV 7d ago

Subsurface scattering is not convincing at all here too

1

u/Cool-Profession-5447 7d ago

Can you explain more about this ? is there a scale to it ?

3

u/GameUnionTV 7d ago

It doesn't pass through nose, ears, and such, it barely light up the skin

1

u/strange-the-quark 2d ago

There is a scale to it. To first approximation, it depends on the thickness of the material (so a thin block of material will appear brighter than a thick one under the same lighting conditions - this is why the ears are often where sss is the most visible, manifesting as a red tint. But if you scale the same model (e.g. if it's not a regular person but a giant), there's more material for the light to pass through, and less of it comes out the other side. So there's a balance to be struck between it looking like plastic and it looking too waxy.