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Tech article on PBR skin rendering (warning: lots of math!)

ToborTobor Posts: 2,300
in The Commons

For those of you who like (very) technical reads, here's a good article from nVidia about proper shading of human skin. Though there's a lot of techie detail in it, and it's not about Iray or Daz Studio specifically, there's some good nuggets and suggestions to be mined.

http://http.developer.nvidia.com/GPUGems3/gpugems3_ch14.html

Comments

  • KaribouKaribou Posts: 1,325

    Lots of PHYSICS, lol.  ;)  (I'm a secondary science teacher, so I tend to think math is only good for physics and chemistry!)  Great article.  Thanks for sharing.

  • larsmidnattlarsmidnatt Posts: 4,511

    Thanks for sharing. One thing to keep in mind is that just like Music, visual Arts don't have to be mathimatical if you don't wise them to be. So for folks fretting over the science or math, you can choose to skip it. Play by ear, or art with your eyes works fine for many.

  • DarkSpartanDarkSpartan Posts: 1,096

    This will help me in the near future, for sure :)

  • SzarkSzark Posts: 10,634

    man I have a headache. :) Thanks Tobor for posting that.

  • jpb06tjpb06t Posts: 272
    edited August 2015

    Lots of thanks. Citing Admiral Kirk "Mr. Saavik, you have to know how starships work"; computer graphics is the same. 

    Post edited by jpb06t on
  • almahiedraalmahiedra Posts: 1,365
    Tobor said:

    For those of you who like (very) technical reads, here's a good article from nVidia about proper shading of human skin. Though there's a lot of techie detail in it, and it's not about Iray or Daz Studio specifically, there's some good nuggets and suggestions to be mined.

    http://http.developer.nvidia.com/GPUGems3/gpugems3_ch14.html

    Excellent article, with a lot of info. The reference (and the references in references) are gems:

    I love these: http://dash.harvard.edu/bitstream/handle/1/4101997/Weyrich_Analysis.pdf?sequence=2

    http://reality.cs.ucl.ac.uk/projects/skinperf/skinperf.pdf

    http://reality.cs.ucl.ac.uk/projects/phd/weyrich-2006-phd.pdf

     

     

  • Half LifeHalf Life Posts: 479

    If you really want to understand skin rendering problems then you should also read this:

    http://gl.ict.usc.edu/Research/SkinStretch/

    When that tech becomes common it will completely change how realistic skin materials are constructed.

  • wizwiz Posts: 1,100

    warning: lots of math!

    Not by my standards, LOL.

    Very enjoyable read. Thank you for the link.

  • IceCrMnIceCrMn Posts: 2,319

    Has anyone tried that example skin shader in the OP link?

    Does it work with Studio?

    How can I try it out if it does?

  • ToborTobor Posts: 2,300

    I see a script (Example 14-6), but it's not in MDL, the base language of Iray shaders. Not sure where to plug this into the D|S material node structure, but I wouldn't be surprise if it's scriptable! In glancing through it, the code appears to also have some HTML conversion issues that'll have to be corrected before it'll run.

  • Arnold CArnold C Posts: 740
    Tobor said:

    For those of you who like (very) technical reads, here's a good article from nVidia about proper shading of human skin. Though there's a lot of techie detail in it, and it's not about Iray or Daz Studio specifically, there's some good nuggets and suggestions to be mined.

    Although the code samples might be a bit outdated (I guess that are those which have been used for the "NVIDIA Demo Team Secrets–Advanced Skin Rendering." Presentation at Game Developer Conference 2007" document, which can be found within the "References" of that article) and presede the current NVIDIA MDL (in the about 8 years since then, I'd expect some development), nevertheless worth reading. Especially the paragraph "Specular Reflectance from Skin Is White" may help DAZ and our fellow PA's to understand why using fancy colors (like grey or blue or whatever) in the Glossy Color slot doesn't make any sense... and is in any case just plain wrong. The presentation PDF includes some useful information, which can be used for Iray shaders, too: page 29 about reflectance properties of skin, page 37 with a more appropriate Refraction Index (1.4) for human skin, page 40 with a representative roughness value, page 49 with a representative value for the thickness of the thin oily layer (Thin Film);

    larsmidnatt said:

    Thanks for sharing. One thing to keep in mind is that just like Music, visual Arts don't have to be mathimatical if you don't wise them to be. So for folks fretting over the science or math, you can choose to skip it. Play by ear, or art with your eyes works fine for many.

    If you'd change that "many" to "some", I'd somewhat agree. And the phrase "artistical freedom" can (and i fear is) also often be just a lame excuse if one is too lazy to get his things straight. Even for "play by ear" you'd need have at least a basic knowledge about music stuff.

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