OpenCV  3.2.0-dev
Open Source Computer Vision
cv::Feature2D Class Reference

Abstract base class for 2D image feature detectors and descriptor extractors. More...

#include "features2d.hpp"

Inheritance diagram for cv::Feature2D:
Collaboration diagram for cv::Feature2D:

Public Member Functions

virtual ~Feature2D ()
 
virtual void clear ()
 Clears the algorithm state. More...
 
virtual void compute (InputArray image, std::vector< KeyPoint > &keypoints, OutputArray descriptors)
 Computes the descriptors for a set of keypoints detected in an image (first variant) or image set (second variant). More...
 
virtual void compute (InputArrayOfArrays images, std::vector< std::vector< KeyPoint > > &keypoints, OutputArrayOfArrays descriptors)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
virtual int defaultNorm () const
 
virtual int descriptorSize () const
 
virtual int descriptorType () const
 
virtual void detect (InputArray image, std::vector< KeyPoint > &keypoints, InputArray mask=noArray())
 Detects keypoints in an image (first variant) or image set (second variant). More...
 
virtual void detect (InputArrayOfArrays images, std::vector< std::vector< KeyPoint > > &keypoints, 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. More...
 
virtual void detectAndCompute (InputArray image, InputArray mask, std::vector< KeyPoint > &keypoints, OutputArray descriptors, bool useProvidedKeypoints=false)
 Detects keypoints and computes the descriptors. More...
 
virtual bool empty () const
 Return true if detector object is empty. More...
 
virtual String getDefaultName () const
 Returns the algorithm string identifier. More...
 
void read (const String &fileName)
 
virtual void read (const FileNode &)
 Reads algorithm parameters from a file storage. More...
 
virtual void save (const String &filename) const
 Saves the algorithm to a file. More...
 
void write (const String &fileName) const
 
virtual void write (FileStorage &) const
 Stores algorithm parameters in a file storage. More...
 

Static Public Member Functions

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

void writeFormat (FileStorage &fs) const
 

Detailed Description

Abstract base class for 2D image feature detectors and descriptor extractors.

Constructor & Destructor Documentation

virtual cv::Feature2D::~Feature2D ( )
virtual

Member Function Documentation

virtual void cv::Algorithm::clear ( )
inlinevirtualinherited

Clears the algorithm state.

Reimplemented in cv::FlannBasedMatcher, cv::DescriptorMatcher, and cv::cuda::DescriptorMatcher.

virtual void cv::Feature2D::compute ( InputArray  image,
std::vector< KeyPoint > &  keypoints,
OutputArray  descriptors 
)
virtual

Computes the descriptors for a set of keypoints detected in an image (first variant) or image set (second variant).

Parameters
imageImage.
keypointsInput collection of keypoints. Keypoints for which a descriptor cannot be computed are removed. Sometimes new keypoints can be added, for example: SIFT duplicates keypoint with several dominant orientations (for each orientation).
descriptorsComputed descriptors. In the second variant of the method descriptors[i] are descriptors computed for a keypoints[i]. Row j is the keypoints (or keypoints[i]) is the descriptor for keypoint j-th keypoint.
virtual void cv::Feature2D::compute ( InputArrayOfArrays  images,
std::vector< std::vector< KeyPoint > > &  keypoints,
OutputArrayOfArrays  descriptors 
)
virtual

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

Parameters
imagesImage set.
keypointsInput collection of keypoints. Keypoints for which a descriptor cannot be computed are removed. Sometimes new keypoints can be added, for example: SIFT duplicates keypoint with several dominant orientations (for each orientation).
descriptorsComputed descriptors. In the second variant of the method descriptors[i] are descriptors computed for a keypoints[i]. Row j is the keypoints (or keypoints[i]) is the descriptor for keypoint j-th keypoint.
virtual int cv::Feature2D::defaultNorm ( ) const
virtual
virtual int cv::Feature2D::descriptorSize ( ) const
virtual
virtual int cv::Feature2D::descriptorType ( ) const
virtual
virtual void cv::Feature2D::detect ( InputArray  image,
std::vector< KeyPoint > &  keypoints,
InputArray  mask = noArray() 
)
virtual

Detects keypoints in an image (first variant) or image set (second variant).

Parameters
imageImage.
keypointsThe detected keypoints. In the second variant of the method keypoints[i] is a set of keypoints detected in images[i] .
maskMask specifying where to look for keypoints (optional). It must be a 8-bit integer matrix with non-zero values in the region of interest.

Reimplemented in cv::AgastFeatureDetector_Impl.

virtual void cv::Feature2D::detect ( InputArrayOfArrays  images,
std::vector< std::vector< KeyPoint > > &  keypoints,
InputArrayOfArrays  masks = noArray() 
)
virtual

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

Parameters
imagesImage set.
keypointsThe detected keypoints. In the second variant of the method keypoints[i] is a set of keypoints detected in images[i] .
masksMasks for each input image specifying where to look for keypoints (optional). masks[i] is a mask for images[i].
virtual void cv::Feature2D::detectAndCompute ( InputArray  image,
InputArray  mask,
std::vector< KeyPoint > &  keypoints,
OutputArray  descriptors,
bool  useProvidedKeypoints = false 
)
virtual

Detects keypoints and computes the descriptors.

virtual bool cv::Feature2D::empty ( ) const
virtual

Return true if detector object is empty.

Reimplemented from cv::Algorithm.

virtual String cv::Algorithm::getDefaultName ( ) const
virtualinherited

Returns the algorithm string identifier.

This string is used as top level xml/yml node tag when the object is saved to a file or string.

template<typename _Tp >
static Ptr<_Tp> cv::Algorithm::load ( const String filename,
const String objname = String() 
)
inlinestaticinherited

Loads algorithm from the file.

Parameters
filenameName of the file to read.
objnameThe optional name of the node to read (if empty, the first top-level node will be used)

This is static template method of Algorithm. It's usage is following (in the case of SVM):

Ptr<SVM> svm = Algorithm::load<SVM>("my_svm_model.xml");

In order to make this method work, the derived class must overwrite Algorithm::read(const FileNode& fn).

References cv::Ptr< T >::empty(), cv::FileNode::empty(), cv::FileStorage::getFirstTopLevelNode(), and cv::FileStorage::READ.

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template<typename _Tp >
static Ptr<_Tp> cv::Algorithm::loadFromString ( const String strModel,
const String objname = String() 
)
inlinestaticinherited

Loads algorithm from a String.

Parameters
strModelThe string variable containing the model you want to load.
objnameThe optional name of the node to read (if empty, the first top-level node will be used)

This is static template method of Algorithm. It's usage is following (in the case of SVM):

Ptr<SVM> svm = Algorithm::loadFromString<SVM>(myStringModel);

References CV_WRAP, cv::Ptr< T >::empty(), cv::FileNode::empty(), cv::FileStorage::getFirstTopLevelNode(), cv::FileStorage::MEMORY, and cv::FileStorage::READ.

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void cv::Feature2D::read ( const String fileName)
virtual void cv::Feature2D::read ( const FileNode fn)
virtual

Reads algorithm parameters from a file storage.

Reimplemented from cv::Algorithm.

virtual void cv::Algorithm::save ( const String filename) const
virtualinherited

Saves the algorithm to a file.

In order to make this method work, the derived class must implement Algorithm::write(FileStorage& fs).

void cv::Feature2D::write ( const String fileName) const
virtual void cv::Feature2D::write ( FileStorage fs) const
virtual

Stores algorithm parameters in a file storage.

Reimplemented from cv::Algorithm.

void cv::Algorithm::writeFormat ( FileStorage fs) const
protectedinherited

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