OpenCV  3.3.1-dev
Open Source Computer Vision
Public Types | Public Member Functions | Static Public Member Functions | List of all members

Class implementing the ORB (oriented BRIEF) keypoint detector and descriptor extractor. More...

#include "features2d.hpp"

Inheritance diagram for cv::ORB:
cv::Feature2D cv::Algorithm cv::cuda::ORB

Public Types

enum  {
  kBytes = 32,
  HARRIS_SCORE =0,
  FAST_SCORE =1
}
 

Public Member Functions

virtual String getDefaultName () const
 
virtual int getEdgeThreshold () const =0
 
virtual int getFastThreshold () const =0
 
virtual int getFirstLevel () const =0
 
virtual int getMaxFeatures () const =0
 
virtual int getNLevels () const =0
 
virtual int getPatchSize () const =0
 
virtual double getScaleFactor () const =0
 
virtual int getScoreType () const =0
 
virtual int getWTA_K () const =0
 
virtual void setEdgeThreshold (int edgeThreshold)=0
 
virtual void setFastThreshold (int fastThreshold)=0
 
virtual void setFirstLevel (int firstLevel)=0
 
virtual void setMaxFeatures (int maxFeatures)=0
 
virtual void setNLevels (int nlevels)=0
 
virtual void setPatchSize (int patchSize)=0
 
virtual void setScaleFactor (double scaleFactor)=0
 
virtual void setScoreType (int scoreType)=0
 
virtual void setWTA_K (int wta_k)=0
 
- Public Member Functions inherited from cv::Feature2D
virtual ~Feature2D ()
 
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)
 
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())
 
virtual void detectAndCompute (InputArray image, InputArray mask, std::vector< KeyPoint > &keypoints, OutputArray descriptors, bool useProvidedKeypoints=false)
 
virtual bool empty () const
 Return true if detector object is empty. More...
 
void read (const String &fileName)
 
virtual void read (const FileNode &)
 Reads algorithm parameters from a file storage. More...
 
void write (const String &fileName) const
 
virtual void write (FileStorage &) const
 Stores algorithm parameters in a file storage. More...
 
void write (const Ptr< FileStorage > &fs, const String &name=String()) const
 
- Public Member Functions inherited from cv::Algorithm
 Algorithm ()
 
virtual ~Algorithm ()
 
virtual void clear ()
 Clears the algorithm state. More...
 
virtual void save (const String &filename) const
 
void write (const Ptr< FileStorage > &fs, const String &name=String()) const
 simplified API for language bindings This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 

Static Public Member Functions

static Ptr< ORBcreate (int nfeatures=500, float scaleFactor=1.2f, int nlevels=8, int edgeThreshold=31, int firstLevel=0, int WTA_K=2, int scoreType=ORB::HARRIS_SCORE, int patchSize=31, int fastThreshold=20)
 The ORB constructor. More...
 
- Static Public Member Functions inherited from cv::Algorithm
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...
 
template<typename _Tp >
static Ptr< _Tp > read (const FileNode &fn)
 Reads algorithm from the file node. More...
 

Additional Inherited Members

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

Detailed Description

Class implementing the ORB (oriented BRIEF) keypoint detector and descriptor extractor.

described in [153] . The algorithm uses FAST in pyramids to detect stable keypoints, selects the strongest features using FAST or Harris response, finds their orientation using first-order moments and computes the descriptors using BRIEF (where the coordinates of random point pairs (or k-tuples) are rotated according to the measured orientation).

Member Enumeration Documentation

§ anonymous enum

anonymous enum
Enumerator
kBytes 
HARRIS_SCORE 
FAST_SCORE 

Member Function Documentation

§ create()

static Ptr<ORB> cv::ORB::create ( int  nfeatures = 500,
float  scaleFactor = 1.2f,
int  nlevels = 8,
int  edgeThreshold = 31,
int  firstLevel = 0,
int  WTA_K = 2,
int  scoreType = ORB::HARRIS_SCORE,
int  patchSize = 31,
int  fastThreshold = 20 
)
static

The ORB constructor.

Parameters
nfeaturesThe maximum number of features to retain.
scaleFactorPyramid decimation ratio, greater than 1. scaleFactor==2 means the classical pyramid, where each next level has 4x less pixels than the previous, but such a big scale factor will degrade feature matching scores dramatically. On the other hand, too close to 1 scale factor will mean that to cover certain scale range you will need more pyramid levels and so the speed will suffer.
nlevelsThe number of pyramid levels. The smallest level will have linear size equal to input_image_linear_size/pow(scaleFactor, nlevels).
edgeThresholdThis is size of the border where the features are not detected. It should roughly match the patchSize parameter.
firstLevelIt should be 0 in the current implementation.
WTA_KThe number of points that produce each element of the oriented BRIEF descriptor. The default value 2 means the BRIEF where we take a random point pair and compare their brightnesses, so we get 0/1 response. Other possible values are 3 and 4. For example, 3 means that we take 3 random points (of course, those point coordinates are random, but they are generated from the pre-defined seed, so each element of BRIEF descriptor is computed deterministically from the pixel rectangle), find point of maximum brightness and output index of the winner (0, 1 or 2). Such output will occupy 2 bits, and therefore it will need a special variant of Hamming distance, denoted as NORM_HAMMING2 (2 bits per bin). When WTA_K=4, we take 4 random points to compute each bin (that will also occupy 2 bits with possible values 0, 1, 2 or 3).
scoreTypeThe default HARRIS_SCORE means that Harris algorithm is used to rank features (the score is written to KeyPoint::score and is used to retain best nfeatures features); FAST_SCORE is alternative value of the parameter that produces slightly less stable keypoints, but it is a little faster to compute.
patchSizesize of the patch used by the oriented BRIEF descriptor. Of course, on smaller pyramid layers the perceived image area covered by a feature will be larger.
fastThreshold

§ getDefaultName()

virtual String cv::ORB::getDefaultName ( ) const
virtual

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.

Reimplemented from cv::Feature2D.

§ getEdgeThreshold()

virtual int cv::ORB::getEdgeThreshold ( ) const
pure virtual

§ getFastThreshold()

virtual int cv::ORB::getFastThreshold ( ) const
pure virtual

§ getFirstLevel()

virtual int cv::ORB::getFirstLevel ( ) const
pure virtual

§ getMaxFeatures()

virtual int cv::ORB::getMaxFeatures ( ) const
pure virtual

§ getNLevels()

virtual int cv::ORB::getNLevels ( ) const
pure virtual

§ getPatchSize()

virtual int cv::ORB::getPatchSize ( ) const
pure virtual

§ getScaleFactor()

virtual double cv::ORB::getScaleFactor ( ) const
pure virtual

§ getScoreType()

virtual int cv::ORB::getScoreType ( ) const
pure virtual

§ getWTA_K()

virtual int cv::ORB::getWTA_K ( ) const
pure virtual

§ setEdgeThreshold()

virtual void cv::ORB::setEdgeThreshold ( int  edgeThreshold)
pure virtual

§ setFastThreshold()

virtual void cv::ORB::setFastThreshold ( int  fastThreshold)
pure virtual

§ setFirstLevel()

virtual void cv::ORB::setFirstLevel ( int  firstLevel)
pure virtual

§ setMaxFeatures()

virtual void cv::ORB::setMaxFeatures ( int  maxFeatures)
pure virtual

§ setNLevels()

virtual void cv::ORB::setNLevels ( int  nlevels)
pure virtual

§ setPatchSize()

virtual void cv::ORB::setPatchSize ( int  patchSize)
pure virtual

§ setScaleFactor()

virtual void cv::ORB::setScaleFactor ( double  scaleFactor)
pure virtual

§ setScoreType()

virtual void cv::ORB::setScoreType ( int  scoreType)
pure virtual

§ setWTA_K()

virtual void cv::ORB::setWTA_K ( int  wta_k)
pure virtual

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