Abstract base class for matching keypoint descriptors. More...

#include <features2d.hpp>

Inheritance diagram for cv::DescriptorMatcher:

Classes
class	DescriptorCollection

Public Types
enum	MatcherType { FLANNBASED = 1 , BRUTEFORCE = 2 , BRUTEFORCE_L1 = 3 , BRUTEFORCE_HAMMING = 4 , BRUTEFORCE_HAMMINGLUT = 5 , BRUTEFORCE_SL2 = 6 }

Public Member Functions
virtual	~DescriptorMatcher ()

virtual CV_WRAP void	add (InputArrayOfArrays descriptors)
	Adds descriptors to train a CPU(trainDescCollectionis) or GPU(utrainDescCollectionis) descriptor collection. More...

CV_WRAP const std::vector< Mat > &	getTrainDescriptors () const
	Returns a constant link to the train descriptor collection trainDescCollection . More...

virtual CV_WRAP void	clear () CV_OVERRIDE
	Clears the train descriptor collections. More...

virtual CV_WRAP bool	empty () const CV_OVERRIDE
	Returns true if there are no train descriptors in the both collections. More...

virtual CV_WRAP bool	isMaskSupported () const =0
	Returns true if the descriptor matcher supports masking permissible matches. More...

virtual CV_WRAP void	train ()
	Trains a descriptor matcher. More...

CV_WRAP void	match (InputArray queryDescriptors, InputArray trainDescriptors, CV_OUT std::vector< DMatch > &matches, InputArray mask=noArray()) const
	Finds the best match for each descriptor from a query set. More...

CV_WRAP void	knnMatch (InputArray queryDescriptors, InputArray trainDescriptors, CV_OUT std::vector< std::vector< DMatch > > &matches, int k, InputArray mask=noArray(), bool compactResult=false) const
	Finds the k best matches for each descriptor from a query set. More...

CV_WRAP void	radiusMatch (InputArray queryDescriptors, InputArray trainDescriptors, CV_OUT std::vector< std::vector< DMatch > > &matches, float maxDistance, InputArray mask=noArray(), bool compactResult=false) const
	For each query descriptor, finds the training descriptors not farther than the specified distance. More...

CV_WRAP void	match (InputArray queryDescriptors, CV_OUT std::vector< DMatch > &matches, InputArrayOfArrays masks=noArray())

CV_WRAP void	knnMatch (InputArray queryDescriptors, CV_OUT std::vector< std::vector< DMatch > > &matches, int k, InputArrayOfArrays masks=noArray(), bool compactResult=false)

CV_WRAP void	radiusMatch (InputArray queryDescriptors, CV_OUT std::vector< std::vector< DMatch > > &matches, float maxDistance, InputArrayOfArrays masks=noArray(), bool compactResult=false)

CV_WRAP void	write (const String &fileName) const

CV_WRAP void	read (const String &fileName)

virtual CV_WRAP void	read (const FileNode &) CV_OVERRIDE
	Reads algorithm parameters from a file storage. More...

virtual void	write (FileStorage &) const CV_OVERRIDE
	Stores algorithm parameters in a file storage. More...

CV_WRAP virtual CV_NODISCARD_STD Ptr< DescriptorMatcher >	clone (bool emptyTrainData=false) const =0
	Clones the matcher. More...

CV_WRAP void	write (FileStorage &fs, const String &name) const

void	write (const Ptr< FileStorage > &fs, const String &name) const

Public Member Functions inherited from cv::Algorithm
	Algorithm ()

virtual	~Algorithm ()

CV_WRAP void	write (FileStorage &fs, const String &name) const

void	write (const Ptr< FileStorage > &fs, const String &name=String()) const

virtual CV_WRAP void	save (const String &filename) const

virtual CV_WRAP String	getDefaultName () const

Static Public Member Functions
static CV_WRAP Ptr< DescriptorMatcher >	create (const String &descriptorMatcherType)
	Creates a descriptor matcher of a given type with the default parameters (using default constructor). More...

static CV_WRAP Ptr< DescriptorMatcher >	create (const DescriptorMatcher::MatcherType &matcherType)

Static Public Member Functions inherited from cv::Algorithm
template<typename _Tp >
static Ptr< _Tp >	read (const FileNode &fn)
	Reads algorithm from the file node. More...

template<typename _Tp >
static Ptr< _Tp >	load (const String &filename, const String &objname=String())
	Loads algorithm from the file. More...

template<typename _Tp >
static Ptr< _Tp >	loadFromString (const String &strModel, const String &objname=String())
	Loads algorithm from a String. More...

Protected Member Functions
virtual void	knnMatchImpl (InputArray queryDescriptors, std::vector< std::vector< DMatch > > &matches, int k, InputArrayOfArrays masks=noArray(), bool compactResult=false)=0

virtual void	radiusMatchImpl (InputArray queryDescriptors, std::vector< std::vector< DMatch > > &matches, float maxDistance, InputArrayOfArrays masks=noArray(), bool compactResult=false)=0

void	checkMasks (InputArrayOfArrays masks, int queryDescriptorsCount) const

Protected Member Functions inherited from cv::Algorithm
void	writeFormat (FileStorage &fs) const

Static Protected Member Functions
static bool	isPossibleMatch (InputArray mask, int queryIdx, int trainIdx)

static bool	isMaskedOut (InputArrayOfArrays masks, int queryIdx)

static CV_NODISCARD_STD Mat	clone_op (Mat m)

Protected Attributes
std::vector< Mat >	trainDescCollection
	Collection of descriptors from train images. More...

std::vector< UMat >	utrainDescCollection

Detailed Description

Abstract base class for matching keypoint descriptors.

It has two groups of match methods: for matching descriptors of an image with another image or with an image set.

Member Enumeration Documentation

◆ MatcherType

enum cv::DescriptorMatcher::MatcherType

Enumerator
FLANNBASED
BRUTEFORCE
BRUTEFORCE_L1
BRUTEFORCE_HAMMING
BRUTEFORCE_HAMMINGLUT
BRUTEFORCE_SL2

Constructor & Destructor Documentation

◆ ~DescriptorMatcher()

virtual cv::DescriptorMatcher::~DescriptorMatcher ( )

virtual

Member Function Documentation

◆ add()

virtual CV_WRAP void cv::DescriptorMatcher::add ( InputArrayOfArrays descriptors )

virtual

Adds descriptors to train a CPU(trainDescCollectionis) or GPU(utrainDescCollectionis) descriptor collection.

If the collection is not empty, the new descriptors are added to existing train descriptors.

Parameters

descriptors Descriptors to add. Each descriptors[i] is a set of descriptors from the same train image.

◆ checkMasks()

void cv::DescriptorMatcher::checkMasks	(	InputArrayOfArrays	masks,
		int	queryDescriptorsCount
	)		const

protected

◆ clear()

virtual CV_WRAP void cv::DescriptorMatcher::clear ( )

virtual

Clears the train descriptor collections.

Reimplemented from cv::Algorithm.

◆ clone()

CV_WRAP virtual CV_NODISCARD_STD Ptr<DescriptorMatcher> cv::DescriptorMatcher::clone ( bool emptyTrainData = false ) const

pure virtual

Clones the matcher.

Parameters

emptyTrainData If emptyTrainData is false, the method creates a deep copy of the object, that is, copies both parameters and train data. If emptyTrainData is true, the method creates an object copy with the current parameters but with empty train data.

Implemented in cv::BFMatcher.

◆ clone_op()

static CV_NODISCARD_STD Mat cv::DescriptorMatcher::clone_op ( Mat m )

inlinestaticprotected

◆ create() [1/2]

static CV_WRAP Ptr<DescriptorMatcher> cv::DescriptorMatcher::create ( const DescriptorMatcher::MatcherType & matcherType )

static

◆ create() [2/2]

static CV_WRAP Ptr<DescriptorMatcher> cv::DescriptorMatcher::create ( const String & descriptorMatcherType )

static

Creates a descriptor matcher of a given type with the default parameters (using default constructor).

Parameters

descriptorMatcherType

Descriptor matcher type. Now the following matcher types are supported:

BruteForce (it uses L2 )
BruteForce-L1
BruteForce-Hamming
BruteForce-Hamming(2)
FlannBased

◆ empty()

virtual CV_WRAP bool cv::DescriptorMatcher::empty ( ) const

virtual

Returns true if there are no train descriptors in the both collections.

Reimplemented from cv::Algorithm.

◆ getTrainDescriptors()

CV_WRAP const std::vector<Mat>& cv::DescriptorMatcher::getTrainDescriptors ( ) const

Returns a constant link to the train descriptor collection trainDescCollection .

◆ isMaskedOut()

static bool cv::DescriptorMatcher::isMaskedOut	(	InputArrayOfArrays	masks,
		int	queryIdx
	)

staticprotected

◆ isMaskSupported()

virtual CV_WRAP bool cv::DescriptorMatcher::isMaskSupported ( ) const

pure virtual

Returns true if the descriptor matcher supports masking permissible matches.

Implemented in cv::BFMatcher.

◆ isPossibleMatch()

static bool cv::DescriptorMatcher::isPossibleMatch	(	InputArray	mask,
		int	queryIdx,
		int	trainIdx
	)

staticprotected

◆ knnMatch() [1/2]

CV_WRAP void cv::DescriptorMatcher::knnMatch	(	InputArray	queryDescriptors,
		CV_OUT std::vector< std::vector< DMatch > > &	matches,
		int	k,
		InputArrayOfArrays	masks = `noArray()`,
		bool	compactResult = `false`
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

queryDescriptors	Query set of descriptors.
matches	Matches. Each matches[i] is k or less matches for the same query descriptor.
k	Count of best matches found per each query descriptor or less if a query descriptor has less than k possible matches in total.
masks	Set of masks. Each masks[i] specifies permissible matches between the input query descriptors and stored train descriptors from the i-th image trainDescCollection[i].
compactResult	Parameter used when the mask (or masks) is not empty. If compactResult is false, the matches vector has the same size as queryDescriptors rows. If compactResult is true, the matches vector does not contain matches for fully masked-out query descriptors.

◆ knnMatch() [2/2]

CV_WRAP void cv::DescriptorMatcher::knnMatch	(	InputArray	queryDescriptors,
		InputArray	trainDescriptors,
		CV_OUT std::vector< std::vector< DMatch > > &	matches,
		int	k,
		InputArray	mask = `noArray()`,
		bool	compactResult = `false`
	)		const

Finds the k best matches for each descriptor from a query set.

Parameters

queryDescriptors	Query set of descriptors.
trainDescriptors	Train set of descriptors. This set is not added to the train descriptors collection stored in the class object.
mask	Mask specifying permissible matches between an input query and train matrices of descriptors.
matches	Matches. Each matches[i] is k or less matches for the same query descriptor.
k	Count of best matches found per each query descriptor or less if a query descriptor has less than k possible matches in total.
compactResult	Parameter used when the mask (or masks) is not empty. If compactResult is false, the matches vector has the same size as queryDescriptors rows. If compactResult is true, the matches vector does not contain matches for fully masked-out query descriptors.

These extended variants of DescriptorMatcher::match methods find several best matches for each query descriptor. The matches are returned in the distance increasing order. See DescriptorMatcher::match for the details about query and train descriptors.

◆ knnMatchImpl()

virtual void cv::DescriptorMatcher::knnMatchImpl	(	InputArray	queryDescriptors,
		std::vector< std::vector< DMatch > > &	matches,
		int	k,
		InputArrayOfArrays	masks = `noArray()`,
		bool	compactResult = `false`
	)

protectedpure virtual

In fact the matching is implemented only by the following two methods. These methods suppose that the class object has been trained already. Public match methods call these methods after calling train().

Implemented in cv::BFMatcher.

◆ match() [1/2]

CV_WRAP void cv::DescriptorMatcher::match	(	InputArray	queryDescriptors,
		CV_OUT std::vector< DMatch > &	matches,
		InputArrayOfArrays	masks = `noArray()`
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

queryDescriptors	Query set of descriptors.
matches	Matches. If a query descriptor is masked out in mask , no match is added for this descriptor. So, matches size may be smaller than the query descriptors count.
masks	Set of masks. Each masks[i] specifies permissible matches between the input query descriptors and stored train descriptors from the i-th image trainDescCollection[i].

◆ match() [2/2]

CV_WRAP void cv::DescriptorMatcher::match	(	InputArray	queryDescriptors,
		InputArray	trainDescriptors,
		CV_OUT std::vector< DMatch > &	matches,
		InputArray	mask = `noArray()`
	)		const

Finds the best match for each descriptor from a query set.

Parameters

queryDescriptors	Query set of descriptors.
trainDescriptors	Train set of descriptors. This set is not added to the train descriptors collection stored in the class object.
matches	Matches. If a query descriptor is masked out in mask , no match is added for this descriptor. So, matches size may be smaller than the query descriptors count.
mask	Mask specifying permissible matches between an input query and train matrices of descriptors.

In the first variant of this method, the train descriptors are passed as an input argument. In the second variant of the method, train descriptors collection that was set by DescriptorMatcher::add is used. Optional mask (or masks) can be passed to specify which query and training descriptors can be matched. Namely, queryDescriptors[i] can be matched with trainDescriptors[j] only if mask.at<uchar>(i,j) is non-zero.

◆ radiusMatch() [1/2]

CV_WRAP void cv::DescriptorMatcher::radiusMatch	(	InputArray	queryDescriptors,
		CV_OUT std::vector< std::vector< DMatch > > &	matches,
		float	maxDistance,
		InputArrayOfArrays	masks = `noArray()`,
		bool	compactResult = `false`
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

queryDescriptors	Query set of descriptors.
matches	Found matches.
maxDistance	Threshold for the distance between matched descriptors. Distance means here metric distance (e.g. Hamming distance), not the distance between coordinates (which is measured in Pixels)!
masks	Set of masks. Each masks[i] specifies permissible matches between the input query descriptors and stored train descriptors from the i-th image trainDescCollection[i].
compactResult	Parameter used when the mask (or masks) is not empty. If compactResult is false, the matches vector has the same size as queryDescriptors rows. If compactResult is true, the matches vector does not contain matches for fully masked-out query descriptors.

◆ radiusMatch() [2/2]

CV_WRAP void cv::DescriptorMatcher::radiusMatch	(	InputArray	queryDescriptors,
		InputArray	trainDescriptors,
		CV_OUT std::vector< std::vector< DMatch > > &	matches,
		float	maxDistance,
		InputArray	mask = `noArray()`,
		bool	compactResult = `false`
	)		const

For each query descriptor, finds the training descriptors not farther than the specified distance.

Parameters

queryDescriptors	Query set of descriptors.
trainDescriptors	Train set of descriptors. This set is not added to the train descriptors collection stored in the class object.
matches	Found matches.
compactResult	Parameter used when the mask (or masks) is not empty. If compactResult is false, the matches vector has the same size as queryDescriptors rows. If compactResult is true, the matches vector does not contain matches for fully masked-out query descriptors.
maxDistance	Threshold for the distance between matched descriptors. Distance means here metric distance (e.g. Hamming distance), not the distance between coordinates (which is measured in Pixels)!
mask	Mask specifying permissible matches between an input query and train matrices of descriptors.

For each query descriptor, the methods find such training descriptors that the distance between the query descriptor and the training descriptor is equal or smaller than maxDistance. Found matches are returned in the distance increasing order.

◆ radiusMatchImpl()

virtual void cv::DescriptorMatcher::radiusMatchImpl	(	InputArray	queryDescriptors,
		std::vector< std::vector< DMatch > > &	matches,
		float	maxDistance,
		InputArrayOfArrays	masks = `noArray()`,
		bool	compactResult = `false`
	)

protectedpure virtual

Implemented in cv::BFMatcher.

◆ read() [1/2]

virtual CV_WRAP void cv::DescriptorMatcher::read ( const FileNode & fn )

virtual

Reads algorithm parameters from a file storage.

Reimplemented from cv::Algorithm.

◆ read() [2/2]

CV_WRAP void cv::DescriptorMatcher::read ( const String & fileName )

inline

◆ train()

virtual CV_WRAP void cv::DescriptorMatcher::train ( )

virtual

Trains a descriptor matcher.

Trains a descriptor matcher (for example, the flann index). In all methods to match, the method train() is run every time before matching. Some descriptor matchers (for example, BruteForceMatcher) have an empty implementation of this method. Other matchers really train their inner structures (for example, FlannBasedMatcher trains flann::Index ).

◆ write() [1/4]

void cv::DescriptorMatcher::write	(	const Ptr< FileStorage > &	fs,
		const String &	name
	)		const

inline

◆ write() [2/4]

CV_WRAP void cv::DescriptorMatcher::write ( const String & fileName ) const

inline

◆ write() [3/4]

virtual void cv::DescriptorMatcher::write ( FileStorage & fs ) const

virtual

Stores algorithm parameters in a file storage.

Reimplemented from cv::Algorithm.

◆ write() [4/4]

CV_WRAP void cv::DescriptorMatcher::write	(	FileStorage &	fs,
		const String &	name
	)		const

inline

Member Data Documentation

◆ trainDescCollection

std::vector<Mat> cv::DescriptorMatcher::trainDescCollection

protected

Collection of descriptors from train images.

◆ utrainDescCollection

std::vector<UMat> cv::DescriptorMatcher::utrainDescCollection

protected

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

build/release/_deps/opencv-src/include/opencv4/opencv2/features2d.hpp

Classes

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

◆ MatcherType

Constructor & Destructor Documentation

◆ ~DescriptorMatcher()

Member Function Documentation

◆ add()

◆ checkMasks()

◆ clear()

◆ clone()

◆ clone_op()

◆ create() [1/2]

◆ create() [2/2]

◆ empty()

◆ getTrainDescriptors()

◆ isMaskedOut()

◆ isMaskSupported()

◆ isPossibleMatch()

◆ knnMatch() [1/2]

◆ knnMatch() [2/2]

◆ knnMatchImpl()

◆ match() [1/2]

◆ match() [2/2]

◆ radiusMatch() [1/2]

◆ radiusMatch() [2/2]

◆ radiusMatchImpl()

◆ read() [1/2]

◆ read() [2/2]

◆ train()

◆ write() [1/4]

◆ write() [2/4]

◆ write() [3/4]

◆ write() [4/4]

Member Data Documentation

◆ trainDescCollection

◆ utrainDescCollection