Light Scattering from Human Hair Fibers

Steve Marschner,
Cornell University
Henrik Wann Jensen,
University of Californa, San Diego
Mike Cammarano,
Stanford University
Steve Worley,
Worley Laboratories
Pat Hanrahan
Stanford University

To appear in Siggraph 2003

Abstract

Light scattering from hair is normally simulated in computer graphics using Kajiya and Kayís classic phenomenological model. We have made new measurements that exhibit visually significant effects not predicted by Kajiya and Kayís model. Our measurements go beyond previous hair measurements by examining out-of-plane scattering, and together with this previous work they show a multiple specular highlight and variation in scattering with rotation about the fiber axis. We explain the sources of these effects using a model of a hair fiber as a transparent elliptical cylinder with an absorbing interior and a surface covered with tilted scales. Based on an analytical scattering function for a circular cylinder, we propose a practical shading model for hair that qualitatively matches the scattering behavior shown in the measurements. In a comparison between a photograph and rendered images, we demonstrate the new modelís ability to match the appearance of real hair.

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Steve Marschner
This page created by Mike Cammarano, Mon 27 Jan 2003, copied by Steve Marschner 3 Feb 2003.
Last modified: Mon 28 Apr 2003.