Implements a sampling strategy that is able to produce paths using bidirectional path tracing or unidirectional volumetric path tracing. More...

#include <mitsuba/bidir/pathsampler.h>

Inheritance diagram for mitsuba::PathSampler:

Public Types
enum	ETechnique { EBidirectional, EUnidirectional }
	Specifies the sampling algorithm that is internally used. More...

typedef boost::function< void(int, int, Float, Path &)>	PathCallback
	Callback type for use with samplePaths() More...

Public Member Functions
	PathSampler (ETechnique technique, const Scene scene, Sampler emitterSampler, Sampler sensorSampler, Sampler directSampler, int maxDepth, int rrDepth, bool excludeDirectIllum, bool sampleDirect, bool lightImage=true)

void	sampleSplats (const Point2i &offset, SplatList &list)
	Generate a sample using the configured sampling strategy. More...

void	samplePaths (const Point2i &offset, PathCallback &callback)
	Sample a series of paths and invoke the specified callback function for each one. More...

Float	generateSeeds (size_t sampleCount, size_t seedCount, bool fineGrained, const Bitmap *importanceMap, std::vector< PathSeed > &seeds)
	Generates a sequence of seeds that are suitable for starting a MLT Markov Chain. More...

Float	computeAverageLuminance (size_t sampleCount)
	Compute the average luminance over the image plane. More...

void	reconstructPath (const PathSeed &seed, const Bitmap *importanceMap, Path &result)
	Reconstruct a path from a PathSeed record. More...

MemoryPool &	getMemoryPool ()
	Return the underlying memory pool. More...

virtual const Class *	getClass () const
	Retrieve this object's class. More...

Public Member Functions inherited from Object
	Object ()
	Construct a new object. More...

int	getRefCount () const
	Return the current reference count. More...

void	incRef () const
	Increase the reference count of the object by one. More...

void	decRef (bool autoDeallocate=true) const
	Decrease the reference count of the object and possibly deallocate it. More...

virtual std::string	toString () const
	Return a human-readable string representation of the object's contents. More...

Static Public Attributes
static Class *	m_theClass

Static Public Attributes inherited from Object
static Class *	m_theClass
	Pointer to the object's class descriptor. More...

Protected Member Functions
virtual	~PathSampler ()
	Virtual destructor. More...

Protected Member Functions inherited from Object
virtual	~Object ()
	Virtual private deconstructor. (Will only be called by ref) More...

Protected Attributes
ETechnique	m_technique

ref< const Scene >	m_scene

ref< SamplingIntegrator >	m_integrator

ref< Sampler >	m_emitterSampler

ref< Sampler >	m_sensorSampler

ref< Sampler >	m_directSampler

int	m_maxDepth

int	m_rrDepth

bool	m_excludeDirectIllum

bool	m_sampleDirect

bool	m_lightImage

int	m_emitterDepth

int	m_sensorDepth

Path	m_emitterSubpath

Path	m_sensorSubpath

Path	m_connectionSubpath

Path	m_fullPath

MemoryPool	m_pool

Additional Inherited Members
Static Public Member Functions inherited from Object
static void	staticInitialization ()
	Initializes the built-in reference count debugger (if enabled) More...

static void	staticShutdown ()
	Free the memory taken by staticInitialization() More...

Detailed Description

Implements a sampling strategy that is able to produce paths using bidirectional path tracing or unidirectional volumetric path tracing.

This versatile class does the heavy lifting under the hood of Mitsuba's PSSMLT implementation. It is also used to provide the Veach-MLT implementation with a luminance estimate and seed paths.

Author: Wenzel Jakob

Member Typedef Documentation

typedef boost::function<void (int, int, Float, Path &)> mitsuba::PathSampler::PathCallback

Callback type for use with samplePaths()

The arguments are (s, t, weight, path) where s denotes the number of steps from the emitter, is the number of steps from the sensor, and weight contains the importance weight associated with the sample.

Member Enumeration Documentation

enum mitsuba::PathSampler::ETechnique

Specifies the sampling algorithm that is internally used.

Enumerator
EBidirectional	Bidirectional path tracing.
EUnidirectional	Unidirectional path tracing (via the 'volpath' plugin)

Constructor & Destructor Documentation

mitsuba::PathSampler::PathSampler	(	ETechnique	technique,
		const Scene *	scene,
		Sampler *	emitterSampler,
		Sampler *	sensorSampler,
		Sampler *	directSampler,
		int	maxDepth,
		int	rrDepth,
		bool	excludeDirectIllum,
		bool	sampleDirect,
		bool	lightImage = `true`
	)

Construct a new path sampler

Parameters

technique	What path generation technique should be used (unidirectional or bidirectional path tracing?)
scene	A pointer to the underlying scene
emitterSampler	Sample generator that should be used for the random walk from the emitter direction
sensorSampler	Sample generator that should be used for the random walk from the sensor direction
directSampler	Sample generator that should be used for direct sampling strategies (or `NULL`, when `sampleDirect=false)`
maxDepth	Maximum path depth to be visualized (-1==infinite)
rrDepth	Depth to begin using russian roulette
excludeDirectIllum	If set to true, the direct illumination component will be ignored. Note that this parameter is unrelated to the next one (sampleDirect) although they are named similarly.
sampleDirect	When this parameter is set to true, specialized direct sampling strategies are used for s=1 and t=1 paths.
lightImage	Denotes whether or not rendering strategies that require a 'light image' (specifically, those with `t==0` or `t==1`) are included in the rendering process.

virtual mitsuba::PathSampler::~PathSampler ( )

protectedvirtual

Virtual destructor.

Member Function Documentation

Float mitsuba::PathSampler::computeAverageLuminance ( size_t sampleCount )

Compute the average luminance over the image plane.

Parameters

sampleCount The number of luminance samples that will be taken

Float mitsuba::PathSampler::generateSeeds	(	size_t	sampleCount,
		size_t	seedCount,
		bool	fineGrained,
		const Bitmap *	importanceMap,
		std::vector< PathSeed > &	seeds
	)

Generates a sequence of seeds that are suitable for starting a MLT Markov Chain.

This function additionally computes the average luminance over the image plane.

Parameters

sampleCount	The number of luminance samples that will be taken
seedCount	The desired number of MLT seeds (must be > `sampleCount`)
fineGrained	This parameter only matters when the technique is set to EBidirectional. It specifies whether to generate PathSeed records at the granularity of entire sensor/emitter subpaths or at the granularity of their constituent sampling strategies.
seeds	A vector of resulting MLT seeds

Returns: The average luminance over the image plane

virtual const Class* mitsuba::PathSampler::getClass ( ) const

virtual

Retrieve this object's class.

Reimplemented from Object.

MemoryPool& mitsuba::PathSampler::getMemoryPool ( )

inline

Return the underlying memory pool.

void mitsuba::PathSampler::reconstructPath	(	const PathSeed &	seed,
		const Bitmap *	importanceMap,
		Path &	result
	)

Reconstruct a path from a PathSeed record.

Given a PathSeed data structure, this function rewinds the random number stream of the underlying ReplayableSampler to the indicated position and recreates the associated path.

void mitsuba::PathSampler::samplePaths	(	const Point2i &	offset,
		PathCallback &	callback
	)

Sample a series of paths and invoke the specified callback function for each one.

This function is similar to sampleSplats(), but instead of returning only the contribution of the samples paths in the form of screen-space "splats", it returns the actual paths by invoking a specified callback function multiple times.

This function is currently only implemented for the bidirectional sampling strategy – i.e. it cannot be used with the unidirectional path tracer.

Parameters

offset	Specifies the desired integer pixel position of the sample. The special value `Point2i(-1)` results in uniform sampling in screen space.
pathCallback	A callback function that will be invoked once for each path generated by the BDPT sampling strategy. The first argument specifies the path importance weight.

void mitsuba::PathSampler::sampleSplats	(	const Point2i &	offset,
		SplatList &	list
	)

Generate a sample using the configured sampling strategy.

The result is stored as a series of screen-space splats (pixel position and spectral value pairs) within the parameter list. These can be used to implement algorithms like Bidirectional Path Tracing or Primary Sample Space MLT.

Parameters

offset	Specifies the desired integer pixel position of the sample. The special value `Point2i(-1)` results in uniform sampling in screen space.
list	Output parameter that will receive a list of splats

Member Data Documentation

Path mitsuba::PathSampler::m_connectionSubpath

protected

ref<Sampler> mitsuba::PathSampler::m_directSampler

protected

int mitsuba::PathSampler::m_emitterDepth

protected

ref<Sampler> mitsuba::PathSampler::m_emitterSampler

protected

Path mitsuba::PathSampler::m_emitterSubpath

protected

bool mitsuba::PathSampler::m_excludeDirectIllum

protected

Path mitsuba::PathSampler::m_fullPath

protected

ref<SamplingIntegrator> mitsuba::PathSampler::m_integrator

protected

bool mitsuba::PathSampler::m_lightImage

protected

int mitsuba::PathSampler::m_maxDepth

protected

MemoryPool mitsuba::PathSampler::m_pool

protected

int mitsuba::PathSampler::m_rrDepth

protected

bool mitsuba::PathSampler::m_sampleDirect

protected

ref<const Scene> mitsuba::PathSampler::m_scene

protected

int mitsuba::PathSampler::m_sensorDepth

protected

ref<Sampler> mitsuba::PathSampler::m_sensorSampler

protected

Path mitsuba::PathSampler::m_sensorSubpath

protected

ETechnique mitsuba::PathSampler::m_technique

protected

Class* mitsuba::PathSampler::m_theClass

static

The documentation for this class was generated from the following file:

include/mitsuba/bidir/pathsampler.h

Public Types

Public Member Functions

Static Public Attributes

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation