“A practical model for subsurface light transport” by Jensen, Marschner, Levoy and Hanrahan

This paper introduces a simple model for subsurface light transport in translucent materials. The model enables efficient simulation of effects that BRDF models cannot capture, such as color bleeding within materials and diffusion of light across shadow boundaries. The technique is efficient even for anisotropic, highly scattering media that are expensive to simulate using existing methods. The model combines an exact solution for single scattering with a dipole point source diffusion approximation for multiple scattering. We also have designed a new, rapid image-based measurement technique for determining the optical properties of translucent materials. We validate the model by comparing predicted and measured values and show how the technique can be used to recover the optical properties of a variety of materials, including milk, marble, and skin. Finally, we describe sampling techniques that allow the model to be used within a conventional ray tracer.

1. S. Chandrasekhar. Radiative Transfer. Oxford Univ. Press, 1960.
2. R. L. Cook, T. Porter, and L. Carpenter. Distributed ray tracing. In ACM Computer Graphics (SIGGRAPH’84), volume 18, pages 137-145, July 1984.
3. P. Debevec, T. Hawkins, C. Tchou, H. Duiker, W. Sarokin, and M. Sagar. Acquiring the reflectance field of a human face. In Computer Graphics Proceedings, Annual Conference Series, 2000, pages 145-156, July 2000.
4. P. E. Debevec and J. Malik. Recovering high dynamic range radiance maps from photographs. In Computer Graphics Proceedings, Annual Conference Series, 1997, pages 369-378, August 1997.
5. J. Dorsey, A. Edelman, H. W. Jensen, J. Legakis, and H. K. Pedersen. Modeling and rendering of weathered stone. In Computer Graphics Proceedings, Annual Conference Series, 1999, pages 225-234, August 1999.
6. G. Eason, A. Veitch, R. Nisbet, and F. Turnbull. The theory of the backscattering of light by blood. J. Physics, 11:1463-1479, 1978.
7. W. G. Egan and T. W. Hilgeman. Optical Properties of Inhomogeneous Materials. Academic Press, New York, 1979.
8. T. J. Farell, M. S. Patterson, and B. Wilson. A diffusion theory model of spatially resolved, steady-state diffuse reflectance for the noninvasive determination of tissue optical properties in vivo. Med. Phys., 19:879-888, 1992.
9. R. A. Groenhuis, H. A. Ferwerda, and J. J. Ten Bosch. Scattering and absorption of turbid materials determined from reflection measurements. 1: Theory. Applied Optics, 22:2456-2462, 1983.
10. P. Hanrahan and W. Krueger. Reflection from layered surfaces due to subsurface scattering. In ACM Computer Graphics (SIGGRAPH’93), pages 165-174, August 1993.
11. L. G. Henyey and J. L. Greenstein. Diffuse radiation in the galaxy. Astrophysics Journal, 93:70-83, 1941.
12. A. Ishimaru. Wave Propagation and Scattering in Random Media, volume 1. Academic Press, New York, 1978.
13. G. Kortum. Reflectance Spectroscopy. Springer-Verlag, 1969.
14. F. E. Nicodemus, J. C. Richmond, J. J. Hsia, I. W. Ginsberg, and T. Limperis. Geometric considerations and nomenclature for reflectance. Monograph 161, National Bureau of Standards (US), October 1977.
15. M. Pharr and P. Hanrahan. Monte Carlo evaluation of non-linear scattering equations for subsurface reflection. In Computer Graphics Proceedings, Annual Conference Series, 2000, pages 75-84, July 2000.
16. L. Reynolds, C. Johnson, and A. Ishimaru. Applied Optics, 15:2059, 1976.
17. J. Stam. Multiple scattering as a diffusion process. In Eurographics Rendering Workshop 1995. Eurographics, June 1995.