Metropolis Light Transport for Participating Media Mark Pauly
- Slides: 17
Metropolis Light Transport for Participating Media Mark Pauly ETH Zürich Thomas Kollig Alexander Keller University of Kaiserslautern EGWR 2000
Overview l Light Transport for Participating Media l Path Integral Formulation l Sampling l Rendering with Metropolis Light Transport l Results l Conclusions EGWR 2000
Related Work MC Methods FE Methods l Zonal Methods ‘ 87 l Rushmeier, Torrance l Hierarchical Radiosity ‘ 93 Pattanaik, Mudur l Spherical Harmonics ‘ 84 l Discrete Ordinates ‘ 94 Languenou, Bouatouch, Chelle Photon Map ‘ 98 Jensen, Christensen Kajiya, von Herzen l Bidirectional Path Tracing ‘ 96 Lafortune, Willems Bhate l Light Tracing ‘ 93 l Metropolis Light Transport ‘ 97 Veach, Guibas EGWR 2000
Light Transport l Global Balance Equation Streaming Emission Absorption In-scattering Out-scattering EGWR 2000
Path Integral Formulation l Measurement Equation l Path Integral EGWR 2000
l Path Characteristic 1 0 medium 1 sensor object 1 light source EGWR 2000
l Path Space Measure EGWR 2000
l Measurement Contribution Function l Path Integral EGWR 2000
Sampling l Line Integral Computation: Ray Marching Equidistant Sampling Stratified Sampling efficient aliasing anti-aliasing inefficient Random Offset Sampling EGWR 2000
Metropolis Light Transport l Generate a random walk path space through l For each path deposit a constant amount of energy at the corresponding pixel l Obtain desired image by distributing paths according to image contribution Metropolis sampling EGWR 2000
l Metropolis Sampling l Propose a mutation of current path l Compute acceptance probability l Choose as new sample if Samples are correlated we can exploit coherence EGWR 2000
l Mutation Strategies l Bidirectional Mutations l large changes to the current path ensures ergodicity Perturbations l l l high acceptance probability changes to image location low cost Scattering Perturbations Sensor Perturbations Propagation Perturbations Caustic Perturbations EGWR 2000
l Propagation Perturbation medium image plane eye light source EGWR 2000
Results EGWR 2000
Results EGWR 2000
Results EGWR 2000
Conclusions l Participating media are fully integrated l l inhomogeneous media multiple, anisotropic scattering volume caustics color bleeding General geometry and reflection models l Robust l l l Complex Scenes Difficult Lighting Situations EGWR 2000
