Metropolis light transport (MLT) is a
global illumination application of a variant of the
Monte Carlo method called the
Metropolis–Hastings algorithm to the
rendering equation for generating images from detailed physical descriptions of
three-dimensional scenes.
The procedure constructs paths from the eye to a light source using
bidirectional path tracing, then constructs slight modifications to the path. Some careful statistical calculation (the Metropolis algorithm) is used to compute the appropriate distribution of brightness over the image. This procedure has the advantage, relative to bidirectional path tracing, that once a path has been found from light to eye, the algorithm can then explore nearby paths; thus difficult-to-find light paths can be explored more thoroughly with the same number of simulated photons. In short, the algorithm generates a path and stores the path's 'nodes' in a list. It can then modify the path by adding extra nodes and creating a new light path. While creating this new path, the algorithm decides how many new 'nodes' to add and whether or not these new nodes will actually create a new path.
Metropolis light transport is an unbiased method that, in some cases (but not always), converges to a solution of the rendering equation faster than other unbiased algorithms such as path tracing or bidirectional path tracing.
Energy Redistribution Path Tracing (ERPT) uses Metropolis sampling-like mutation strategies instead of an intermediate
probability distribution
In probability theory and statistics, a probability distribution is the mathematical function that gives the probabilities of occurrence of different possible outcomes for an experiment. It is a mathematical description of a random phenomenon i ...
step.
See also
*
Nicholas Metropolis – The physicist after whom the algorithm is named
''Renderers using MLT:''
*
Arion
Arion (; grc-gre, Ἀρίων; fl. c. 700 BC) was a kitharode in ancient Greece, a Dionysiac poet credited with inventing the dithyramb. The islanders of Lesbos claimed him as their native son, but Arion found a patron in Periander, tyrant ...
– A commercial unbiased renderer based on path tracing and providing an MLT sampler
*
Indigo Renderer – A commercial unbiased 3D renderer that uses MLT
*
Irayexternal link – An unbiased renderer that has an option for MLT
*
Kerkythea – A free unbiased 3D renderer that uses MLT
*
LuxRender – An open source unbiased renderer that uses MLT
*
Mitsuba Rendererweb site A research-oriented renderer which implements several MLT variants
*
Octane Render – An commercial unbiased renderer that uses MLT
*
Unicorn Renderweb site – A commercial unbiased render providing MTL sampler and Caustic sampler
References
External links
Metropolis project at StanfordHomepage of the Mitsuba rendererLuxRender - an open source render engine that supports MLTKerkythea 2008 - a freeware rendering system that uses MLTA Practical Introduction to Metropolis Light TransportUnbiased physically based rendering on the GPU
Monte Carlo methods
Global illumination algorithms
{{compu-stub