documentation improvements, some subtle gui improvements, revived MEMLT
Wenzel Jakob
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789312b5e3
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91b9668aa0
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doc/main.bib
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doc/main.bib
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@ -515,3 +515,17 @@
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pages={531--540},
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year={2002}
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}
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@article{Jakob2012Manifold,
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author = {Jakob, Wenzel and Marschner, Steve},
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title = {{Manifold Exploration: a Markov Chain Monte Carlo technique for rendering scenes with difficult specular transport}},
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journal = {ACM Trans. Graph.},
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volume = {31},
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number = {4},
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month = jul,
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year = {2012},
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pages = {58:1--58:13},
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publisher = {ACM},
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address = {New York, NY, USA}
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}
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@ -40,10 +40,6 @@ MTS_NAMESPACE_BEGIN
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* \code{2} will lead to single-bounce (direct-only) illumination,
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* and so on. \default{\code{-1}}
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* }
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* \parameter{rrDepth}{\Integer}{Specifies the minimum path depth, after
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* which the implementation will start to use the ``russian roulette''
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* path termination criterion. \default{\code{5}}
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* }
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* \parameter{luminanceSamples}{\Integer}{
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* MLT-type algorithms create output images that are only
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* \emph{relative}. The algorithm can e.g. determine that a certain pixel
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@ -53,23 +49,78 @@ MTS_NAMESPACE_BEGIN
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* number of samples. \default{\code{100000} samples}
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* }
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* \parameter{twoStage}{\Boolean}{Use two-stage MLT?
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* See below for details. \default{{\footnotesize\code{false}}}}
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* \parameter{bidirectional\showbreak Mutation, [lens,caustic,multiChain]\showbreak Perturbation}{\Boolean}{
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* These parameters can be used to choose the mutation strategies that
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* should be used. By default, only the bidirectional mutation is
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* enabled.
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* See \pluginref{pssmlt} for details.\!\default{{\footnotesize\code{false}}}\!}
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* \parameter{bidirectional\showbreak\newline Mutation,\vspace{1mm}
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* [lens,multiChain,\newline caustic,manifold]\showbreak\newline Perturbation}{\Boolean}{
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* These parameters can be used to pick the individual mutation and perturbation
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* strategies that will be used to explore path space. By default, the original set
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* by Veach and Guibas is enabled (i.e. everything except the manifold
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* perturbation). It is possible to extend
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* this integrator with additional custom perturbations strategies if needed.
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* }
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* \parameter{lambda}{\Float}{
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* Jump size of the manifold perturbation \default{50}}
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* }
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* Metropolis Light Transport is a seminal rendering technique proposed by Veach and
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* Metropolis Light Transport (MLT) is a seminal rendering technique proposed by Veach and
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* Guibas \cite{Veach1997Metropolis}, which applies the Metropolis-Hastings
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* algorithm to the problem of light transport in the path-space setting.
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*
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* algorithm to the path-space formulation of light transport.
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* Please refer to the \pluginref{pssmlt} page for a general description of MLT-type
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* algorithms and a list of caveats that also apply to this plugin.
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*
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* Like \pluginref{pssmlt}, this integrator explores the space of light paths,
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* searching with preference for those that carry a significant amount of
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* energy from an emitter to the sensor. The main difference is that PSSMLT
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* does this exploration by piggybacking on another rendering technique and
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* ``manipulating'' the random number stream that drives it, whereas MLT does
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* not use such an indirection: it operates directly on the actual light
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* paths.
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*
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* This means that the algorithm has access to considerably more
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* information about the problem to be solved, which allows it to perform a
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* directed exploration of certain classes of light paths. The main downside
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* is that the implementation is rather complex, which may make it more
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* susceptible to unforeseen problems.
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* Mitsuba reproduces the full MLT
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* algorithm except for the lens subpath mutation\footnote{In experiments,
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* it was not found to produce sigificant convergence improvements and was
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* subsequently removed.}. In addition, the plugin also provides the
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* manifold perturbation proposed by Jakob and Marschner \cite{Jakob2012Manifold}.
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*
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* \renderings{
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* \vspace{-2mm}
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* \includegraphics[width=\textwidth]{images/integrator_mlt_sketch.pdf}\hfill\,
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* \vspace{-3mm}
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* \caption{The available mutation types}
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* }
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*
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* To explore the space of light paths, MLT iteratively makes changes
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* to a light path, which can either be large-scale \emph{mutations} or small-scale
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* \emph{perturbations}. Roughly speaking, the \emph{bidirectional mutation} is used
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* to jump between different classes of light paths, and each one of the perturbations is
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* responsible for efficiently exploring some of these classes.
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* All mutation and perturbation strategies can be mixed and matched as
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* desired, though for the algorithm to work properly, the bidirectional
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* mutation must be active and perturbations should be selected
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* as required based on the types of light paths that are present in the
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* input scene. The following perturbations are available:
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*
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* \begin{enumerate}[(a)]
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* \item \emph{Lens perturbation}: this perturbation slightly varies the outgoing
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* direction at the camera and propagates the resulting ray until it encounters
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* the first non-specular object. The perturbation then attempts to create a connection to the
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* (unchanged) remainder of the path.
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* \item \emph{Caustic perturbation}: essentially a lens perturbation
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* that proceeds in the opposite direction.
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* \item \emph{Multi-chain perturbation}: used when there are several chains
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* of specular interactions, as seen in the swimming pool example above.
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* After an initial lens perturbation, a cascade of additional perturbations
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* is required until a connection to the (unchanged)
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* remainder of the path can finally be established.
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* \item \emph{Manifold perturbation}: this perturbation was designed to
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* subsume and extend the previous three approaches.
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* It creates a perturbation at an arbitrary
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* position along the path, proceeding in either direction. Upon encountering
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* a chain of specular interactions, it numerically solves for a
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* connection path (as opposed to the cascading mechanism employed by the
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* multi-chain perturbation).
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* \end{enumerate}
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*/
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class MLT : public Integrator {
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public:
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@ -130,17 +181,17 @@ public:
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m_config.bidirectionalMutation = props.getBoolean("bidirectionalMutation", true);
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/* Selectively enable/disable the lens perturbation */
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m_config.lensPerturbation = props.getBoolean("lensPerturbation", false);
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m_config.lensPerturbation = props.getBoolean("lensPerturbation", true);
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/* Selectively enable/disable the caustic perturbation */
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m_config.causticPerturbation = props.getBoolean("causticPerturbation", false);
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m_config.causticPerturbation = props.getBoolean("causticPerturbation", true);
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/* Selectively enable/disable the multi-chain perturbation */
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m_config.multiChainPerturbation = props.getBoolean("multiChainPerturbation", false);
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m_config.multiChainPerturbation = props.getBoolean("multiChainPerturbation", true);
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/* Selectively enable/disable the manifold perturbation */
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m_config.manifoldPerturbation = props.getBoolean("manifoldPerturbation", false);
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m_config.probFactor = props.getFloat("probFactor", 50);
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m_config.probFactor = props.getFloat("probFactor", props.getFloat("lambda", 50));
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/* Stop MLT after X seconds -- useful for equal-time comparisons */
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m_config.timeout = props.getInteger("timeout", 0);
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@ -143,7 +143,8 @@ public:
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#endif
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for (size_t mutationCtr=0; mutationCtr < m_config.nMutations
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&& !stop; ++mutationCtr) {
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if (wu->getTimeout() > 0 && (mutationCtr % 8192) == 0 && (int) timer->getMilliseconds() > wu->getTimeout())
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if (wu->getTimeout() > 0 && (mutationCtr % 8192) == 0 &&
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(int) timer->getMilliseconds() > wu->getTimeout())
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break;
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/* Query all mutators for their suitability */
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@ -203,7 +204,26 @@ public:
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suitabilities.normalize();
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Float Qyx = mutator->Q(*proposed, *current, muRec.reverse()) * suitabilities[mutatorIdx];
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Float a = std::min((Float) 1, Qyx / Qxy);
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Float a;
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if (!m_config.importanceMap) {
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a = std::min((Float) 1, Qyx / Qxy);
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} else {
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const Float *luminanceValues = m_config.importanceMap->getFloatData();
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const Point2 &curPos = current->getSamplePosition();
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const Point2 &propPos = proposed->getSamplePosition();
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Vector2i size = m_config.importanceMap->getSize();
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Point2i curPosI(
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std::min(std::max(0, (int) curPos.x), size.x-1),
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std::min(std::max(0, (int) curPos.y), size.y-1));
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Point2i propPosI(
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std::min(std::max(0, (int) propPos.x), size.x-1),
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std::min(std::max(0, (int) propPos.y), size.y-1));
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Float curValue = luminanceValues[curPosI.x + curPosI.y * size.x];
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Float propValue = luminanceValues[propPosI.x + propPosI.y * size.x];
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a = std::min((Float) 1, (Qyx * curValue) / (Qxy * propValue));
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}
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#if defined(MTS_BD_DEBUG_HEAVY)
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if (!proposed->verify(m_scene, EImportance, oss)) {
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@ -327,8 +347,14 @@ void MLTProcess::develop() {
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/* Compute the luminance correction factor */
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Float avgLuminance = 0;
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for (size_t i=0; i<pixelCount; ++i)
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avgLuminance += accum[i].getLuminance();
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if (importanceMap) {
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for (size_t i=0; i<pixelCount; ++i)
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avgLuminance += accum[i].getLuminance() * importanceMap[i];
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} else {
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for (size_t i=0; i<pixelCount; ++i)
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avgLuminance += accum[i].getLuminance();
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}
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avgLuminance /= (Float) pixelCount;
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Float luminanceFactor = m_config.luminance / avgLuminance;
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@ -290,6 +290,7 @@ void PSSMLTProcess::develop() {
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for (size_t i=0; i<pixelCount; ++i)
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avgLuminance += accum[i].getLuminance();
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}
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avgLuminance /= (Float) pixelCount;
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Float luminanceFactor = m_config.luminance / avgLuminance;
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@ -239,9 +239,6 @@ bool ManifoldPerturbation::sampleMutation(
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}
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}
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cout << source.toString() << endl;
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cout << "a=" << a << ", b=" << b << ", c=" << c << endl;
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ETransportMode mode = (step == 1) ? EImportance : ERadiance;
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int l = std::min(a, c), m = std::max(a, c);
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int q = std::min(b, b+step);
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@ -589,13 +586,6 @@ bool ManifoldPerturbation::sampleMutation(
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}
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}
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}
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cout << "BEFORE: " << q << endl;
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cout << source.vertex(q)->toString() << endl;
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cout << " and " << source.vertex(q+1)->toString() << endl;
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cout << "AFTER: " << endl;
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cout << proposal.vertex(q)->toString() << endl;
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cout << " and " << proposal.vertex(q+1)->toString() << endl;
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if (!PathVertex::connect(m_scene,
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proposal.vertexOrNull(q-1),
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proposal.edgeOrNull(q-1),
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@ -408,21 +408,27 @@ void GLWidget::timerImpulse() {
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}
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if (!(m_mouseDrag && m_navigationMode == EStandard) && !m_animation) {
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Float moveSpeed = m_context->movementScale
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ProjectiveCamera *camera = getProjectiveCamera();
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Float delta = m_context->movementScale
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* m_clock->getMilliseconds();
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if (m_leftKeyDown)
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setInverseViewTransform(getInverseViewTransform() *
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Transform::translate(Vector(moveSpeed,0,0)));
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Transform::translate(Vector(delta,0,0)));
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if (m_rightKeyDown)
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setInverseViewTransform(getInverseViewTransform() *
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Transform::translate(Vector(-moveSpeed,0,0)));
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if (m_downKeyDown)
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Transform::translate(Vector(-delta,0,0)));
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if (m_downKeyDown) {
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setInverseViewTransform(getInverseViewTransform() *
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Transform::translate(Vector(0,0,-moveSpeed)));
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if (m_upKeyDown)
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Transform::translate(Vector(0,0,-delta)));
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camera->setFocusDistance(camera->getFocusDistance() + delta);
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}
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if (m_upKeyDown) {
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setInverseViewTransform(getInverseViewTransform() *
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Transform::translate(Vector(0,0,moveSpeed)));
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Transform::translate(Vector(0,0,delta)));
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camera->setFocusDistance(camera->getFocusDistance() - delta);
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}
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}
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m_clock->reset();
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@ -432,6 +432,8 @@ void MainWindow::on_actionDuplicateTab_triggered() {
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currentIndex = m_contextIndex;
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SceneContext *currentContext = m_context[currentIndex];
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SceneContext *newContext = new SceneContext(currentContext);
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if (currentContext->renderJob)
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newContext->windowSize -= currentContext->sizeIncrease;
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m_contextMutex.lock();
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m_context.append(newContext);
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@ -532,13 +532,13 @@
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<param name="bidirectionalMutation" readableName="Bidirectional mutation" type="boolean" default="true" importance="1">
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Selectively enable/disable the bidirectional mutation
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</param>
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<param name="lensPerturbation" readableName="Lens perturbation" type="boolean" default="false" importance="1">
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<param name="lensPerturbation" readableName="Lens perturbation" type="boolean" default="true" importance="1">
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Selectively enable/disable the lens perturbation
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</param>
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<param name="causticPerturbation" readableName="Caustic perturbation" type="boolean" default="false" importance="1">
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<param name="causticPerturbation" readableName="Caustic perturbation" type="boolean" default="true" importance="1">
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Selectively enable/disable the caustic perturbation
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</param>
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<param name="multiChainPerturbation" readableName="Multi-chain perturbation" type="boolean" default="false" importance="1">
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<param name="multiChainPerturbation" readableName="Multi-chain perturbation" type="boolean" default="true" importance="1">
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Selectively enable/disable the multi-chain perturbation
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</param>
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<param name="manifoldPerturbation" readableName="Manifold perturbation" type="boolean" default="false" importance="1">
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@ -592,16 +592,16 @@
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<param name="bidirectionalMutation" readableName="Bidirectional mutation" type="boolean" default="false" importance="1">
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Selectively enable/disable the bidirectional mutation
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</param>
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<param name="lensPerturbation" readableName="Lens perturbation" type="boolean" default="false" importance="1">
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<param name="lensPerturbation" readableName="Lens perturbation" type="boolean" default="true" importance="1">
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Selectively enable/disable the lens perturbation
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</param>
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<param name="causticPerturbation" readableName="Caustic perturbation" type="boolean" default="false" importance="1">
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<param name="causticPerturbation" readableName="Caustic perturbation" type="boolean" default="true" importance="1">
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Selectively enable/disable the caustic perturbation
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</param>
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<param name="multiChainPerturbation" readableName="Multi-chain perturbation" type="boolean" default="false" importance="1">
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<param name="multiChainPerturbation" readableName="Multi-chain perturbation" type="boolean" default="true" importance="1">
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Selectively enable/disable the multi-chain perturbation
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</param>
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<param name="manifoldPerturbation" readableName="Manifold perturbation" type="boolean" default="true" importance="1">
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<param name="manifoldPerturbation" readableName="Manifold perturbation" type="boolean" default="false" importance="1">
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Selectively enable/disable the manifold perturbation
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</param>
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<param name="probFactor" readableName="Probability factor" type="float" default="50" importance="1">
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