Manifold exploration

Wenzel Jakob, Steve Marschner
2012 ACM Transactions on Graphics  
Figure 1 : Two views of an interior scene with complex specular and near-specular transport, rendered using manifold exploration path tracing: (a) Refractive, reflective, and glossy tableware, (b) A brass luminaire with 24 glass-enclosed bulbs used to light the previous closeup. Abstract It is a long-standing problem in unbiased Monte Carlo methods for rendering that certain difficult types of light transport paths, particularly those involving viewing and illumination along paths containing
more » ... cular or glossy surfaces, cause unusably slow convergence. In this paper we introduce Manifold Exploration, a new way of handling specular paths in rendering. It is based on the idea that sets of paths contributing to the image naturally form manifolds in path space, which can be explored locally by a simple equationsolving iteration. This paper shows how to formulate and solve the required equations using only geometric information that is already generally available in ray tracing systems, and how to use this method in in two different Markov Chain Monte Carlo frameworks to accurately compute illumination from general families of paths. The resulting rendering algorithms handle specular, near-specular, glossy, and diffuse surface interactions as well as isotropic or highly anisotropic volume scattering interactions, all using the same fundamental algorithm. An implementation is demonstrated on a range of challenging scenes and evaluated against previous methods. Links: DL PDF WEB VIDEO CODE 1 Because it is possible to have several separated specular paths joining two points, the parameterization cannot be global.
doi:10.1145/2185520.2185554 fatcat:yecmb55k75flja2bekhezxfqdy