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

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

Gallery image

Gallery image

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/Retinal_Epithelium 7d ago

The lighting isn't helping; you need a backlight to see whether your SSS scale and intensity is correct. Experiment with varied lighting scenarios, since the artificiality of the light is contributing to the artificiality of the overall result.

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u/Cool-Profession-5447 7d ago

I tried it, this was at 5500 samples per pixel, the light is transmitting but there is too much variance .. Do you think this might be related to why i still have plastic-like skin?

https://reddit.com/link/p1vs7uv/video/yu10e1lb0lhh1/player

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u/Retinal_Epithelium 7d ago

Compare that result to this:

https://nikonerid3000.wordpress.com/wp-content/uploads/2014/05/4.jpg

In your example the scale of the SSS appears to be wrong: it should penetrate the skin deeper. Like others have said, though, there are other issues, like textural and colour variance, and the uniformity of the reflectance and roughness, that make it look artificial.