Bidirectional Rendering of Polarized Light Transport

Abstract

On the foundations of many rendering algorithm is the symmetry between the path traversed by light and its adjoint from the camera. However, several effects, including polarization or fluorescence, break that symmetry and are defined only on the direction of light. This complicates the applicability of bidirectional methods, that exploit the symmetry for effective rendering light transport. In this work we focus on how to include polarization within a bidirectional rendering algorithm. For that, we generalize the path integral to support the constraints imposed by non-symmetric light transport. Based on this theoretical framework, we propose modifications on two bidirectional methods, namely bidirectional path tracing and photon mapping, extending them to support polarization.