Light Scattering in Human Hair Fibers

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Light Scattering in Human Hair Fibers
Pjotter Tommassen
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Hair

• Very Translucent
• Not just reflection
• Light also transmitted
• Transmitted light also reflected

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Scatter Function (1/2)

• Light Scattering in Human Hair Fibers presents
  a scatter function
• Function has four inputs
• ?i Lightsource inclination
• ?r Viewer inclination
• Fi Lightsource Azimuth
• Fr Viewer Azimuth

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Scatter Function (2/2)

• Function very complex
• Use lookup texture
• Scatter Function derived to two two-dimensional
  functions
• Can be precalculated using two 2D-textures!

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Tweaks

• By changing the lookup textures, hair becomes
  tweakable
• Refraction
• Absorption
• Surface Scales
• Glints

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Sources

• Marschner, S. R., e.a. Light scattering from
  human hair fibers. ACM Trans. Graph. 22, 3 (Jul.
  2003), 780-791
• Wlokam, M. M., Advanced Rendering Techniques.
  Nvidia Corporation