Abstract sensor interface. More...

#include <mitsuba/render/sensor.h>

Inheritance diagram for mitsuba::Sensor:

Public Types
enum	ESensorFlags { EDeltaTime = 0x010, ENeedsApertureSample = 0x020, EProjectiveCamera = 0x100, EPerspectiveCamera = 0x200, EOrthographicCamera = 0x400, EPositionSampleMapsToPixels = 0x1000, EDirectionSampleMapsToPixels = 0x2000 }
	This list of flags is used to additionally characterize and classify the response functions of different types of sensors. More...

Public Types inherited from mitsuba::AbstractEmitter
enum	EEmitterType { EDeltaDirection = 0x01, EDeltaPosition = 0x02, EOnSurface = 0x04 }
	Flags used to classify the emission profile of different types of emitters. More...

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

Additional sensor-related sampling functions
virtual Spectrum	sampleRay (Ray &ray, const Point2 &samplePosition, const Point2 &apertureSample, Float timeSample) const =0
	Importance sample a ray according to the sensor response. More...

virtual Spectrum	sampleRayDifferential (RayDifferential &ray, const Point2 &samplePosition, const Point2 &apertureSample, Float timeSample) const
	Importance sample a ray differential according to the sensor response. More...

Float	sampleTime (Float sample) const
	Importance sample the temporal part of the sensor response function. More...

Additional query functions
virtual Spectrum	eval (const Intersection &its, const Vector &d, Point2 &samplePos) const
	Return the emitted importance for the given surface intersection. More...

virtual bool	getSamplePosition (const PositionSamplingRecord &pRec, const DirectionSamplingRecord &dRec, Point2 &position) const
	Return the sample position associated with a given position and direction sampling record. More...

Float	pdfTime (const Ray &ray, EMeasure measure) const
	Evaluate the temporal component of the sampling density implemented by the sampleRay() method. More...

Float	getShutterOpen () const
	Return the time value of the shutter opening event. More...

void	setShutterOpen (Float time)
	Set the time value of the shutter opening event. More...

Float	getShutterOpenTime () const
	Return the length, for which the shutter remains open. More...

void	setShutterOpenTime (Float time)
	Set the length, for which the shutter remains open. More...

bool	needsTimeSample () const
	Does the method sampleRay() require a uniformly distributed sample for the time-dependent component? More...

Miscellaneous
bool	needsApertureSample () const
	Does the method sampleRay() require a uniformly distributed sample for the aperture component? More...

Film *	getFilm ()
	Return the Film instance associated with this sensor. More...

const Film *	getFilm () const
	Return the Film instance associated with this sensor (const) More...

Float	getAspect () const
	Return the aspect ratio of the sensor and its underlying film. More...

Sampler *	getSampler ()
	Return the sensor's sample generator. More...

const Sampler *	getSampler () const
	Return the sensor's sampler (const version). More...

virtual void	serialize (Stream stream, InstanceManager manager) const
	Serialize this sensor to a binary data stream. More...

ConfigurableObject interface
virtual void	addChild (const std::string &name, ConfigurableObject *child)
	Add a child ConfigurableObject. More...

void	addChild (ConfigurableObject *child)
	Add an unnamed child. More...

virtual void	configure ()
	Configure the object (called once after construction and addition of all child ConfigurableObject instances). More...

Public Member Functions inherited from mitsuba::AbstractEmitter
virtual Spectrum	samplePosition (PositionSamplingRecord &pRec, const Point2 &sample, const Point2 *extra=NULL) const
	Importance sample the spatial component of the emission profile. More...

virtual Spectrum	sampleDirection (DirectionSamplingRecord &dRec, PositionSamplingRecord &pRec, const Point2 &sample, const Point2 *extra=NULL) const
	Conditioned on the spatial component, importance sample the directional part of the emission profile. More...

virtual Spectrum	sampleDirect (DirectSamplingRecord &dRec, const Point2 &sample) const
	Direct sampling: given a reference point in the scene, sample an emitter position that contributes towards it. More...

virtual Spectrum	evalPosition (const PositionSamplingRecord &pRec) const
	Evaluate the spatial component of the emission profile. More...

virtual Spectrum	evalDirection (const DirectionSamplingRecord &dRec, const PositionSamplingRecord &pRec) const
	Evaluate the directional component of the emission profile. More...

virtual Float	pdfPosition (const PositionSamplingRecord &pRec) const
	Evaluate the spatial component of the sampling density implemented by the samplePosition() method. More...

virtual Float	pdfDirection (const DirectionSamplingRecord &dRec, const PositionSamplingRecord &pRec) const
	Evaluate the directional component of the sampling density implemented by the sampleDirection() method. More...

virtual Float	pdfDirect (const DirectSamplingRecord &dRec) const
	Evaluate the probability density of the direct sampling method implemented by the sampleDirect() method. More...

uint32_t	getType () const
	Return a listing of classification flags combined using binary OR. More...

const AnimatedTransform *	getWorldTransform () const
	Return the local space to world space transformation. More...

void	setWorldTransform (AnimatedTransform *trafo)
	Set the local space to world space transformation. More...

bool	needsPositionSample () const
	Does the method samplePosition() require a uniformly distributed sample for the spatial component? More...

bool	needsDirectionSample () const
	Does the method sampleDirection() require a uniformly distributed sample for the direction component? More...

bool	isOnSurface () const
	Does the emitter lie on some kind of surface? More...

bool	isDegenerate () const
	Does the sensor have a degenerate directional or spatial distribution? More...

bool	needsDirectSample () const
	Does the method sampleDirect() require a uniformly distributed sample? More...

EMeasure	getDirectMeasure () const
	Return the measure associated with the sampleDirect() operation. More...

Medium *	getMedium ()
	Return a pointer to the medium that surrounds the emitter. More...

const Medium *	getMedium () const
	Return a pointer to the medium that surrounds the emitter (const version) More...

Shape *	getShape ()
	Return the shape, to which the emitter is currently attached. More...

const Shape *	getShape () const
	Return the shape, to which the emitter is currently attached (const version) More...

virtual ref< Shape >	createShape (const Scene *scene)
	Create a special shape that represents the emitter. More...

virtual AABB	getAABB () const =0
	Return an axis-aligned box bounding the spatial extents of the emitter. More...

void	setMedium (Medium *medium)
	Set the medium that surrounds the emitter. More...

void	addChild (ConfigurableObject *child)
	Add an unnamed child. More...

Public Member Functions inherited from mitsuba::ConfigurableObject
virtual void	setParent (ConfigurableObject *parent)
	Notify the ConfigurableObject instance about its parent object. More...

void	addChild (ConfigurableObject *child)
	Add an unnamed child. More...

const std::string &	getID () const
	Return the identifier associated with this instance (or "unnamed") More...

void	setID (const std::string &name)
	Set the identifier associated with this instance. More...

const Properties &	getProperties () const
	Return the properties object that was originally used to create this instance. More...

Public Member Functions inherited from mitsuba::SerializableObject
	SerializableObject (Stream stream, InstanceManager manager)
	Unserialize a serializable object. 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 mitsuba::AbstractEmitter
static Class *	m_theClass

Static Public Attributes inherited from mitsuba::ConfigurableObject
static Class *	m_theClass

Static Public Attributes inherited from mitsuba::SerializableObject
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
	Sensor (const Properties &props)
	Construct a new sensor instance. More...

	Sensor (Stream stream, InstanceManager manager)
	Unserialize a sensor instance from a binary data stream. More...

virtual	~Sensor ()
	Virtual destructor. More...

Protected Member Functions inherited from mitsuba::AbstractEmitter
	AbstractEmitter (const Properties &props)
	Construct a new emitter instance. More...

	AbstractEmitter (Stream stream, InstanceManager manager)
	Unserialize a emitter instance from a binary data stream. More...

virtual	~AbstractEmitter ()
	Virtual destructor. More...

Protected Member Functions inherited from mitsuba::ConfigurableObject
virtual	~ConfigurableObject ()
	Virtual destructor. More...

	ConfigurableObject (const Properties &props)
	Construct a configurable object. More...

	ConfigurableObject (Stream stream, InstanceManager manager)
	Unserialize a configurable object. More...

Protected Member Functions inherited from mitsuba::SerializableObject
	SerializableObject ()
	Construct a serializable object. More...

virtual	~SerializableObject ()
	Virtual deconstructor. More...

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

Protected Attributes
ref< Film >	m_film

ref< Sampler >	m_sampler

Vector2	m_resolution

Vector2	m_invResolution

Float	m_shutterOpen

Float	m_shutterOpenTime

Float	m_aspect

Protected Attributes inherited from mitsuba::AbstractEmitter
ref< const AnimatedTransform >	m_worldTransform

ref< Medium >	m_medium

Shape *	m_shape

uint32_t	m_type

Protected Attributes inherited from mitsuba::ConfigurableObject
Properties	m_properties

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

Abstract sensor interface.

This class provides an abstract interface to all sensor plugins in Mitsuba. It exposes functions for evaluating and sampling the response function of the sensor, and it allows querying the probability density of the sampling method.

Somewhat curiously, the Sensor class derives from AbstractEmitter. The reason for this is that much like radiance, the spectral response of a sensor can be interpreted as emitted quantity named importance. The Sensor interface thus inherits almost all of the emitter API and only needs to add a few camera-specific methods on top.

The concept of interpreting sensor response as an emitted quantity and the resulting flexibility of being able to dynamically transition between emitter and receiver interpretations of luminaires and sensors is a key insight that enables the construction of powerful bidirectional rendering techniques It is the reason why the API to these components may seem somewhat unorthodox.

In Mitsuba, a sensor can be as simple as an irradiance meter that performs a single measurement along a specified ray, but it can also represent sensors that are more commonly used in computer graphics, such as a perspective camera based on the thin lens equation.

An important difference between a luminaire and a sensor is that the sensor records spectral measurements to a film, and for that reason it needs a mapping between rays and film pixel coordinates. Apart from that, the interfaces are almost identical.

Mitsuba assumes that a sensor always has a form of "shutter", which opens for a certain time, during which the exposure takes place. The sensor itself may also undergo motion while the shutter is open, but a more complicated dependence on time is not allowed.

Member Enumeration Documentation

enum mitsuba::Sensor::ESensorFlags

This list of flags is used to additionally characterize and classify the response functions of different types of sensors.

See Also: AbstractEmitter::EEmitterType

Enumerator
EDeltaTime	Sensor response contains a Dirac delta term with respect to time.
ENeedsApertureSample	Does the sampleRay() function need an aperture sample?
EProjectiveCamera	Is the sensor a projective camera?
EPerspectiveCamera	Is the sensor a perspective camera?
EOrthographicCamera	Is the sensor an orthographic camera?
EPositionSampleMapsToPixels	Does the sample given to samplePosition() determine the pixel coordinates.
EDirectionSampleMapsToPixels	Does the sample given to sampleDirection() determine the pixel coordinates.

Constructor & Destructor Documentation

mitsuba::Sensor::Sensor ( const Properties & props )

protected

Construct a new sensor instance.

mitsuba::Sensor::Sensor	(	Stream *	stream,
		InstanceManager *	manager
	)

protected

Unserialize a sensor instance from a binary data stream.

virtual mitsuba::Sensor::~Sensor ( )

protectedvirtual

Virtual destructor.

Member Function Documentation

virtual void mitsuba::Sensor::addChild	(	const std::string &	name,
		ConfigurableObject *	child
	)

virtual

Add a child ConfigurableObject.

Reimplemented from mitsuba::AbstractEmitter.

void mitsuba::Sensor::addChild ( ConfigurableObject * child )

inline

Add an unnamed child.

virtual void mitsuba::Sensor::configure ( )

virtual

Configure the object (called once after construction and addition of all child ConfigurableObject instances).

Reimplemented from mitsuba::ConfigurableObject.

Reimplemented in mitsuba::PerspectiveCamera.

virtual Spectrum mitsuba::Sensor::eval	(	const Intersection &	its,
		const Vector &	d,
		Point2 &	samplePos
	)		const

virtual

Return the emitted importance for the given surface intersection.

This is function is used when a sensor has been hit by a ray in a particle tracing-style integrator, and it subsequently needs to be queried for the emitted importance along the negative ray direction.

It efficiently computes the product of evalPosition() and evalDirection(), though note that it does not include the cosine foreshortening factor of the latter method.

This function is provided here as a fast convenience function for unidirectional rendering techniques that support intersecting the sensor. The default implementation throws an exception, which states that the method is not implemented.

Parameters

its	An intersect record that specfies the query position
d	A unit vector, which specifies the query direction
result	This argument is used to return the 2D sample position (i.e. the fractional pixel coordinates) associated with the intersection.

Returns: The emitted importance

Remarks: In the Python API, the signature of this function is spectrum, samplePos = sensor.eval(its, d)

Float mitsuba::Sensor::getAspect ( ) const

inline

Return the aspect ratio of the sensor and its underlying film.

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

virtual

Retrieve this object's class.

Reimplemented from mitsuba::AbstractEmitter.

Reimplemented in mitsuba::PerspectiveCamera, and mitsuba::ProjectiveCamera.

Film* mitsuba::Sensor::getFilm ( )

inline

Return the Film instance associated with this sensor.

const Film* mitsuba::Sensor::getFilm ( ) const

inline

Return the Film instance associated with this sensor (const)

virtual bool mitsuba::Sensor::getSamplePosition	(	const PositionSamplingRecord &	pRec,
		const DirectionSamplingRecord &	dRec,
		Point2 &	position
	)		const

virtual

Return the sample position associated with a given position and direction sampling record.

Parameters

dRec	A direction sampling record, which specifies the query direction
pRec	A position sampling record, which specifies the query position

Returns: true if the specified ray is visible by the camera

Remarks: In the Python API, the signature of this function is visible, position = sensor.getSamplePosition(pRec, dRec)

Sampler* mitsuba::Sensor::getSampler ( )

inline

Return the sensor's sample generator.

This is the root sampler, which will later be cloned a number of times to provide each participating worker thread with its own instance (see Scene::getSampler()). Therefore, this sampler should never be used for anything except creating clones.

const Sampler* mitsuba::Sensor::getSampler ( ) const

inline

Return the sensor's sampler (const version).

This is the root sampler, which will later be cloned a number of times to provide each participating worker thread with its own instance (see Scene::getSampler()). Therefore, this sampler should never be used for anything except creating clones.

Float mitsuba::Sensor::getShutterOpen ( ) const

inline

Return the time value of the shutter opening event.

Float mitsuba::Sensor::getShutterOpenTime ( ) const

inline

Return the length, for which the shutter remains open.

bool mitsuba::Sensor::needsApertureSample ( ) const

inline

Does the method sampleRay() require a uniformly distributed sample for the aperture component?

bool mitsuba::Sensor::needsTimeSample ( ) const

inline

Does the method sampleRay() require a uniformly distributed sample for the time-dependent component?

Float mitsuba::Sensor::pdfTime	(	const Ray &	ray,
		EMeasure	measure
	)		const

Evaluate the temporal component of the sampling density implemented by the sampleRay() method.

virtual Spectrum mitsuba::Sensor::sampleRay	(	Ray &	ray,
		const Point2 &	samplePosition,
		const Point2 &	apertureSample,
		Float	timeSample
	)		const

pure virtual

Importance sample a ray according to the sensor response.

This function combines all three of the steps of sampling a time, ray position, and direction value. It does not return any auxiliary sampling information and is mainly meant to be used by unidirectional rendering techniques.

Note that this function potentially uses a different sampling strategy compared to the sequence of running sampleArea() and sampleDirection(). The reason for this is that it may be possible to switch to a better technique when sampling both position and direction at the same time.

Parameters

ray	A ray data structure to be populated with a position and direction value
samplePosition	Denotes the desired sample position in fractional pixel coordinates relative to the crop window of the underlying film.
apertureSample	A uniformly distributed 2D vector that is used to sample a position on the aperture of the sensor if necessary. (Any value is valid when needsApertureSample() == `false`)
timeSample	A uniformly distributed 1D vector that is used to sample the temporal component of the emission profile. (Or any value when needsTimeSample() == `false`)

Returns: An importance weight associated with the sampled ray. This accounts for the difference between the sensor response and the sampling density function.

Remarks: In the Python API, the signature of this function is spectrum, ray = sensor.sampleRay(samplePosition, apertureSample)

virtual Spectrum mitsuba::Sensor::sampleRayDifferential	(	RayDifferential &	ray,
		const Point2 &	samplePosition,
		const Point2 &	apertureSample,
		Float	timeSample
	)		const

virtual

Importance sample a ray differential according to the sensor response.

This function combines all three of the steps of sampling a time, ray position, and direction value. It does not return any auxiliary sampling information and is mainly meant to be used by unidirectional rendering techniques.

Note that this function potentially uses a different sampling strategy compared to the sequence of running sampleArea() and sampleDirection(). The reason for this is that it may be possible to switch to a better technique when sampling both position and direction at the same time.

The default implementation computes differentials using several internal calls to sampleRay(). Subclasses of the Sensor interface may optionally provide a more efficient approach.

Parameters

ray	A ray data structure to be populated with a position and direction value
samplePosition	Denotes the desired sample position in fractional pixel coordinates relative to the crop window of the underlying film.
apertureSample	A uniformly distributed 2D vector that is used to sample a position on the aperture of the sensor if necessary. (Any value is valid when needsApertureSample() == `false`)
timeSample	A uniformly distributed 1D vector that is used to sample the temporal component of the emission profile. (Or any value when needsTimeSample() == `false`)

Returns: An importance weight associated with the sampled ray. This accounts for the difference between the sensor response and the sampling density function.

Remarks: In the Python API, the signature of this function is spectrum, ray = sensor.sampleRayDifferential(samplePosition, apertureSample)

Float mitsuba::Sensor::sampleTime ( Float sample ) const

inline

Importance sample the temporal part of the sensor response function.

virtual void mitsuba::Sensor::serialize	(	Stream *	stream,
		InstanceManager *	manager
	)		const

virtual

Serialize this sensor to a binary data stream.

Reimplemented from mitsuba::AbstractEmitter.

Reimplemented in mitsuba::PerspectiveCamera, and mitsuba::ProjectiveCamera.

void mitsuba::Sensor::setShutterOpen ( Float time )

inline

Set the time value of the shutter opening event.

void mitsuba::Sensor::setShutterOpenTime ( Float time )

Set the length, for which the shutter remains open.

Member Data Documentation

Float mitsuba::Sensor::m_aspect

protected

ref<Film> mitsuba::Sensor::m_film

protected

Vector2 mitsuba::Sensor::m_invResolution

protected

Vector2 mitsuba::Sensor::m_resolution

protected

ref<Sampler> mitsuba::Sensor::m_sampler

protected

Float mitsuba::Sensor::m_shutterOpen

protected

Float mitsuba::Sensor::m_shutterOpenTime

protected

Class* mitsuba::Sensor::m_theClass

static

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

include/mitsuba/render/sensor.h

Public Types

Public Member Functions

Static Public Attributes

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation