Ray tracing with polarization parameters

摘要

Incorporating polarization parameters into the lighting model can enhance the physical realism of images rendered with a ray tracer. Polarization effects can be important in certain scenes, and the difference in rendering even simple scenes with and without proper treatment of polarization can be striking. All light waves possess a state of polarization, which changes almost every time light reflects off a material surface. A single reflection partially polarizes and may even completely polarize previously unpolarized light. Polarization influences the rendering of a scene because the reflected radiant intensity depends largely on the incident light waves's polarization state. E. Wolf's (1959) coherence matrix formalism of polarization has been incorporated into the Torrance-Sparrow reflectance model. This combination allows elegant quantitative derivations of the altered polarization state of light upon reflection in a ray tracer. Comparisons of identical scenes rendered with a conventional ray tracer and the ray tracer presented incorporating a polarization model show that the present method renders specular interobject reflections more accurately with respect to reflected radiance and color.