Detailed Description

A generic 2D feature from an image, extracted with CFeatureExtraction Each feature may have one or more descriptors (see descriptors), in addition to an image patch.

The (Euclidean) distance between descriptors in a pair of features can be computed with descriptorDistanceTo, while the similarity of the patches is given by patchCorrelationTo.

See also:: CFeatureList, TSimpleFeature, TSimpleFeatureList

#include <mrpt/vision/CFeature.h>

Inheritance diagram for mrpt::vision::CFeature:

[legend]

List of all members.

Classes
struct	TDescriptors
	All the possible descriptors this feature may have. More...
Public Member Functions
bool	isPointFeature () const
	Return false only for Blob detectors (SIFT, SURF)
bool	getFirstDescriptorAsMatrix (mrpt::math::CMatrixFloat &desc) const
	Return the first found descriptor, as a matrix.
float	patchCorrelationTo (const CFeature &oFeature) const
	Computes the normalized cross-correlation between the patches of this and another feature (normalized in the range [0,1], such as 0=best, 1=worst).
float	descriptorDistanceTo (const CFeature &oFeature, TDescriptorType descriptorToUse=descAny, bool normalize_distances=true) const
	Computes the Euclidean Distance between this feature's and other feature's descriptors, using the given descriptor or the first present one.
float	descriptorSIFTDistanceTo (const CFeature &oFeature, bool normalize_distances=true) const
	Computes the Euclidean Distance between "this" and the "other" descriptors.
float	descriptorSURFDistanceTo (const CFeature &oFeature, bool normalize_distances=true) const
	Computes the Euclidean Distance between "this" and the "other" descriptors.
float	descriptorSpinImgDistanceTo (const CFeature &oFeature, bool normalize_distances=true) const
	Computes the Euclidean Distance between "this" and the "other" descriptors.
float	descriptorPolarImgDistanceTo (const CFeature &oFeature, float &minDistAngle, bool normalize_distances=true) const
	Returns the minimum Euclidean Distance between "this" and the "other" polar image descriptor, for the best shift in orientation.
float	descriptorLogPolarImgDistanceTo (const CFeature &oFeature, float &minDistAngle, bool normalize_distances=true) const
	Returns the minimum Euclidean Distance between "this" and the "other" log-polar image descriptor, for the best shift in orientation.
void	saveToTextFile (const std::string &filename, bool APPEND=false)
	Save the feature to a text file in this format: "%% Dump of mrpt::vision::CFeatureList. Each line format is:\n" "%% ID TYPE X Y ORIENTATION SCALE TRACK_STATUS RESPONSE HAS_SIFT [SIFT] HAS_SURF [SURF] HAS_MULTI [MULTI]_i" "%% \|---------------------- feature ------------------\| \|---------------------- descriptors ------------------------\|" "%% with:\n" "%% TYPE : The used detector: 0:KLT, 1: Harris, 2: BCD, 3: SIFT, 4: SURF, 5: Beacon, 6: FAST\n" "%% HAS_* : 1 if a descriptor of that type is associated to the feature." "%% SIFT : Present if HAS_SIFT=1: N DESC_0 ... DESC_N-1" "%% SURF : Present if HAS_SURF=1: N DESC_0 ... DESC_N-1" "%% MULTI : Present if HAS_MULTI=1: SCALE ORI N DESC_0 ... DESC_N-1" "%%-------------------------------------------------------------------------------------------\n");.
TFeatureType	get_type () const
	Get the type of the feature.
void	dumpToTextStream (mrpt::utils::CStream &out) const
	Dump feature information into a text stream.
void	dumpToConsole () const
	CFeature ()
	Constructor.
virtual	~CFeature ()
	Virtual destructor.
mrpt::utils::CObjectPtr	duplicateGetSmartPtr () const
	Returns a copy of the object, indepently of its class, as a smart pointer (the newly created object will exist as long as any copy of this smart pointer).
CObject *	clone () const
	Cloning interface for smart pointers.
Public Attributes
float	x
float	y
	Coordinates in the image.
TFeatureID	ID
	ID of the feature.
CImage	patch
	A patch of the image surrounding the feature.
uint16_t	patchSize
	Size of the patch (patchSize x patchSize) (it must be an odd number)
TFeatureType	type
	Type of the feature: featNotDefined, featSIFT, featKLT, featHarris, featSURF, featBeacon.
TFeatureTrackStatus	track_status
	Status of the feature tracking process (old name: KLT_status)
float	response
	A measure of the "goodness" of the feature (old name: KLT_val)
float	orientation
	Main orientation of the feature.
float	scale
	Feature scale into the scale space.
uint8_t	user_flags
	A field for any other flags needed by the user (this has not a predefined meaning)
uint16_t	nTimesSeen
	Number of frames it has been seen in a sequence of images.
uint16_t	nTimesNotSeen
	Number of frames it has not been seen in a sequence of images.
uint16_t	nTimesLastSeen
	Number of frames since it was seen for the last time.
double	depth
	The estimated depth in 3D of this feature wrt the camera in the current frame.
double	initialDepth
	The estimated depth in 3D of this feature wrt the camera that took its image.
TPoint3D	p3D
	The estimated 3D point of this feature wrt its camera.
deque< double >	multiScales
	A set of scales where the multi-resolution descriptor has been computed.
deque< vector< double > >	multiOrientations
	A vector of main orientations (there is a vector of orientations for each scale)
deque< vector< vector< int32_t > > >	multiHashCoeffs
	A set of vectors containing the coefficients for a HASH table of descriptors.
struct VISION_IMPEXP mrpt::vision::CFeature::TDescriptors	descriptors
Static Public Attributes
static const mrpt::utils::TRuntimeClassId	classCObject
Protected Member Functions
virtual void	writeToStream (mrpt::utils::CStream &out, int *getVersion) const =0
	Introduces a pure virtual method responsible for writing to a CStream.
virtual void	readFromStream (mrpt::utils::CStream &in, int version)=0
	Introduces a pure virtual method responsible for loading from a CStream This can not be used directly be users, instead use "stream >> object;" for reading it from a stream or "stream >> object_ptr;" if the class is unknown apriori.
Static Protected Member Functions
static float	internal_distanceBetweenPolarImages (const mrpt::math::CMatrix &desc1, const mrpt::math::CMatrix &desc2, float &minDistAngle, bool normalize_distances, bool dont_shift_angle)
	Internal function used by "descriptorLogPolarImgDistanceTo" and "descriptorPolarImgDistanceTo".
Friends
class	CFeatureList
class	CMatchedFeatureList
RTTI stuff
class	mrpt::utils::CStream
static const mrpt::utils::TRuntimeClassId	classCSerializable
RTTI stuff
typedef CFeaturePtr	SmartPtr
static mrpt::utils::CLASSINIT	_init_CFeature
static mrpt::utils::TRuntimeClassId	classCFeature
static const mrpt::utils::TRuntimeClassId *	classinfo
static const mrpt::utils::TRuntimeClassId *	_GetBaseClass ()
virtual const mrpt::utils::TRuntimeClassId *	GetRuntimeClass () const
	Returns information about the class of an object in runtime.
virtual mrpt::utils::CObject *	duplicate () const
	Returns a copy of the object, indepently of its class.
static mrpt::utils::CObject *	CreateObject ()
static CFeaturePtr	Create ()

Member Typedef Documentation

typedef CFeaturePtr mrpt::vision::CFeature::SmartPtr

A typedef for the associated smart pointer

Definition at line 83 of file CFeature.h.

Constructor & Destructor Documentation

mrpt::vision::CFeature::CFeature ( )

Constructor.

virtual mrpt::vision::CFeature::~CFeature ( ) [inline, virtual]

Virtual destructor.

Definition at line 207 of file CFeature.h.

Member Function Documentation

static const mrpt::utils::TRuntimeClassId* mrpt::vision::CFeature::_GetBaseClass ( ) [static, protected]

Reimplemented from mrpt::utils::CSerializable.

CObject* mrpt::utils::CObject::clone ( ) const [inline, inherited]

Cloning interface for smart pointers.

Reimplemented in mrpt::opengl::CRenderizable, and mrpt::opengl::CRenderizableDisplayList.

Definition at line 154 of file CObject.h.

static CFeaturePtr mrpt::vision::CFeature::Create ( ) [static]

static mrpt::utils::CObject* mrpt::vision::CFeature::CreateObject ( ) [static]

float mrpt::vision::CFeature::descriptorDistanceTo	(	const CFeature &	oFeature,
		TDescriptorType	descriptorToUse = `descAny`,
		bool	normalize_distances = `true`
	)		const

Computes the Euclidean Distance between this feature's and other feature's descriptors, using the given descriptor or the first present one.

Note:: If descriptorToUse is not descAny and that descriptor is not present in one of the features, an exception will be raised.

See also:: patchCorrelationTo

float mrpt::vision::CFeature::descriptorLogPolarImgDistanceTo	(	const CFeature &	oFeature,
		float &	minDistAngle,
		bool	normalize_distances = `true`
	)		const

Returns the minimum Euclidean Distance between "this" and the "other" log-polar image descriptor, for the best shift in orientation.

Parameters:

oFeature	The other feature to compare with.
minDistAngle	The placeholder for the angle at which the smallest distance is found.

Returns:: The distance for the best orientation (minimum distance).

float mrpt::vision::CFeature::descriptorPolarImgDistanceTo	(	const CFeature &	oFeature,
		float &	minDistAngle,
		bool	normalize_distances = `true`
	)		const

Returns the minimum Euclidean Distance between "this" and the "other" polar image descriptor, for the best shift in orientation.

Parameters:

oFeature	The other feature to compare with.
minDistAngle	The placeholder for the angle at which the smallest distance is found.

Returns:: The distance for the best orientation (minimum distance).

float mrpt::vision::CFeature::descriptorSIFTDistanceTo	(	const CFeature &	oFeature,
		bool	normalize_distances = `true`
	)		const

Computes the Euclidean Distance between "this" and the "other" descriptors.

float mrpt::vision::CFeature::descriptorSpinImgDistanceTo	(	const CFeature &	oFeature,
		bool	normalize_distances = `true`
	)		const

Computes the Euclidean Distance between "this" and the "other" descriptors.

float mrpt::vision::CFeature::descriptorSURFDistanceTo	(	const CFeature &	oFeature,
		bool	normalize_distances = `true`
	)		const

Computes the Euclidean Distance between "this" and the "other" descriptors.

void mrpt::vision::CFeature::dumpToConsole ( ) const

void mrpt::vision::CFeature::dumpToTextStream ( mrpt::utils::CStream & out ) const

Dump feature information into a text stream.

virtual mrpt::utils::CObject* mrpt::vision::CFeature::duplicate ( ) const [virtual]

Returns a copy of the object, indepently of its class.

Implements mrpt::utils::CObject.

mrpt::utils::CObjectPtr mrpt::utils::CObject::duplicateGetSmartPtr ( ) const [inline, inherited]

Returns a copy of the object, indepently of its class, as a smart pointer (the newly created object will exist as long as any copy of this smart pointer).

Definition at line 151 of file CObject.h.

TFeatureType mrpt::vision::CFeature::get_type ( ) const [inline]

Get the type of the feature.

Definition at line 195 of file CFeature.h.

bool mrpt::vision::CFeature::getFirstDescriptorAsMatrix ( mrpt::math::CMatrixFloat & desc ) const

Return the first found descriptor, as a matrix.

Returns:: false on error, i.e. there is no valid descriptor.

virtual const mrpt::utils::TRuntimeClassId* mrpt::vision::CFeature::GetRuntimeClass ( ) const [virtual]

Returns information about the class of an object in runtime.

Reimplemented from mrpt::utils::CSerializable.

static float mrpt::vision::CFeature::internal_distanceBetweenPolarImages	(	const mrpt::math::CMatrix &	desc1,
		const mrpt::math::CMatrix &	desc2,
		float &	minDistAngle,
		bool	normalize_distances,
		bool	dont_shift_angle
	)		`[static, protected]`

Internal function used by "descriptorLogPolarImgDistanceTo" and "descriptorPolarImgDistanceTo".

bool mrpt::vision::CFeature::isPointFeature ( ) const

Return false only for Blob detectors (SIFT, SURF)

float mrpt::vision::CFeature::patchCorrelationTo ( const CFeature & oFeature ) const

Computes the normalized cross-correlation between the patches of this and another feature (normalized in the range [0,1], such as 0=best, 1=worst).

Note:: If this or the other features does not have patches or they are of different sizes, an exception will be raised.

See also:: descriptorDistanceTo

virtual void mrpt::utils::CSerializable::readFromStream	(	mrpt::utils::CStream &	in,
		int	version
	)		`[protected, pure virtual, inherited]`

Introduces a pure virtual method responsible for loading from a CStream This can not be used directly be users, instead use "stream >> object;" for reading it from a stream or "stream >> object_ptr;" if the class is unknown apriori.

Parameters:

in	The input binary stream where the object data must read from.
version	The version of the object stored in the stream: use this version number in your code to know how to read the incoming data.

Exceptions:

std::exception On any error, see CStream::ReadBuffer

See also:: CStream

Implemented in mrpt::math::CMatrixD, and mrpt::math::CMatrix.

void mrpt::vision::CFeature::saveToTextFile	(	const std::string &	filename,
		bool	APPEND = `false`
	)

Save the feature to a text file in this format: "%% Dump of mrpt::vision::CFeatureList. Each line format is:\n" "%% ID TYPE X Y ORIENTATION SCALE TRACK_STATUS RESPONSE HAS_SIFT [SIFT] HAS_SURF [SURF] HAS_MULTI [MULTI]_i" "%% |---------------------- feature ------------------| |---------------------- descriptors ------------------------|" "%% with:\n" "%% TYPE : The used detector: 0:KLT, 1: Harris, 2: BCD, 3: SIFT, 4: SURF, 5: Beacon, 6: FAST\n" "%% HAS_* : 1 if a descriptor of that type is associated to the feature." "%% SIFT : Present if HAS_SIFT=1: N DESC_0 ... DESC_N-1" "%% SURF : Present if HAS_SURF=1: N DESC_0 ... DESC_N-1" "%% MULTI : Present if HAS_MULTI=1: SCALE ORI N DESC_0 ... DESC_N-1" "%%-------------------------------------------------------------------------------------------\n");.

virtual void mrpt::utils::CSerializable::writeToStream	(	mrpt::utils::CStream &	out,
		int *	getVersion
	)		const `[protected, pure virtual, inherited]`

Introduces a pure virtual method responsible for writing to a CStream.

This can not be used directly be users, instead use "stream << object;" for writing it to a stream.

Parameters:

out	The output binary stream where object must be dumped.
getVersion	If NULL, the object must be dumped. If not, only the version of the object dump must be returned in this pointer. This enables the versioning of objects dumping and backward compatibility with previously stored data.

Exceptions:

std::exception On any error, see CStream::WriteBuffer