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Public Member Functions | Static Public Member Functions | List of all members
cv::SIFT Class Referenceabstract
2D Features Framework » Feature Detection and Description

Class for extracting keypoints and computing descriptors using the Scale Invariant Feature Transform (SIFT) algorithm by D. Lowe [Lowe04] . More...

#include <features2d.hpp>

Inheritance diagram for cv::SIFT:
cv::Feature2D cv::Algorithm

Public Member Functions

virtual CV_WRAP String getDefaultName () const CV_OVERRIDE
 
virtual CV_WRAP void setNFeatures (int maxFeatures)=0
 
virtual CV_WRAP int getNFeatures () const =0
 
virtual CV_WRAP void setNOctaveLayers (int nOctaveLayers)=0
 
virtual CV_WRAP int getNOctaveLayers () const =0
 
virtual CV_WRAP void setContrastThreshold (double contrastThreshold)=0
 
virtual CV_WRAP double getContrastThreshold () const =0
 
virtual CV_WRAP void setEdgeThreshold (double edgeThreshold)=0
 
virtual CV_WRAP double getEdgeThreshold () const =0
 
virtual CV_WRAP void setSigma (double sigma)=0
 
virtual CV_WRAP double getSigma () const =0
 
- Public Member Functions inherited from cv::Feature2D
virtual ~Feature2D ()
 
virtual CV_WRAP void detect (InputArray image, CV_OUT std::vector< KeyPoint > &keypoints, InputArray mask=noArray())
 Detects keypoints in an image (first variant) or image set (second variant).
 
virtual CV_WRAP void detect (InputArrayOfArrays images, CV_OUT std::vector< std::vector< KeyPoint > > &keypoints, InputArrayOfArrays masks=noArray())
 
virtual CV_WRAP void compute (InputArray image, CV_OUT CV_IN_OUT 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).
 
virtual CV_WRAP void compute (InputArrayOfArrays images, CV_OUT CV_IN_OUT std::vector< std::vector< KeyPoint > > &keypoints, OutputArrayOfArrays descriptors)
 
virtual CV_WRAP void detectAndCompute (InputArray image, InputArray mask, CV_OUT std::vector< KeyPoint > &keypoints, OutputArray descriptors, bool useProvidedKeypoints=false)
 
virtual CV_WRAP int descriptorSize () const
 
virtual CV_WRAP int descriptorType () const
 
virtual CV_WRAP int defaultNorm () const
 
CV_WRAP void write (const String &fileName) const
 
CV_WRAP void read (const String &fileName)
 
virtual void write (FileStorage &) const CV_OVERRIDE
 Stores algorithm parameters in a file storage.
 
virtual CV_WRAP void read (const FileNode &) CV_OVERRIDE
 Reads algorithm parameters from a file storage.
 
virtual CV_WRAP bool empty () const CV_OVERRIDE
 Return true if detector object is empty.
 
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 ()
 
virtual CV_WRAP void clear ()
 Clears the algorithm state.
 
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
 

Static Public Member Functions

static CV_WRAP Ptr< SIFT > create (int nfeatures=0, int nOctaveLayers=3, double contrastThreshold=0.04, double edgeThreshold=10, double sigma=1.6, bool enable_precise_upscale=false)
 
static CV_WRAP Ptr< SIFT > create (int nfeatures, int nOctaveLayers, double contrastThreshold, double edgeThreshold, double sigma, int descriptorType, bool enable_precise_upscale=false)
 Create SIFT with specified descriptorType.
 
- Static Public Member Functions inherited from cv::Algorithm
template<typename _Tp >
static Ptr< _Tp > read (const FileNode &fn)
 Reads algorithm from the file node.
 
template<typename _Tp >
static Ptr< _Tp > load (const String &filename, const String &objname=String())
 Loads algorithm from the file.
 
template<typename _Tp >
static Ptr< _Tp > loadFromString (const String &strModel, const String &objname=String())
 Loads algorithm from a String.
 

Additional Inherited Members

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

Detailed Description

Class for extracting keypoints and computing descriptors using the Scale Invariant Feature Transform (SIFT) algorithm by D. Lowe [Lowe04] .

Member Function Documentation

◆ create() [1/2]

static CV_WRAP Ptr< SIFT > cv::SIFT::create ( int  nfeatures,
int  nOctaveLayers,
double  contrastThreshold,
double  edgeThreshold,
double  sigma,
int  descriptorType,
bool  enable_precise_upscale = false 
)
static

Create SIFT with specified descriptorType.

Parameters
nfeaturesThe number of best features to retain. The features are ranked by their scores (measured in SIFT algorithm as the local contrast)
nOctaveLayersThe number of layers in each octave. 3 is the value used in D. Lowe paper. The number of octaves is computed automatically from the image resolution.
contrastThresholdThe contrast threshold used to filter out weak features in semi-uniform (low-contrast) regions. The larger the threshold, the less features are produced by the detector.
Note
The contrast threshold will be divided by nOctaveLayers when the filtering is applied. When nOctaveLayers is set to default and if you want to use the value used in D. Lowe paper, 0.03, set this argument to 0.09.
Parameters
edgeThresholdThe threshold used to filter out edge-like features. Note that the its meaning is different from the contrastThreshold, i.e. the larger the edgeThreshold, the less features are filtered out (more features are retained).
sigmaThe sigma of the Gaussian applied to the input image at the octave #0. If your image is captured with a weak camera with soft lenses, you might want to reduce the number.
descriptorTypeThe type of descriptors. Only CV_32F and CV_8U are supported.
enable_precise_upscaleWhether to enable precise upscaling in the scale pyramid, which maps index $\texttt{x}$ to $\texttt{2x}$. This prevents localization bias. The option is disabled by default.

◆ create() [2/2]

static CV_WRAP Ptr< SIFT > cv::SIFT::create ( int  nfeatures = 0,
int  nOctaveLayers = 3,
double  contrastThreshold = 0.04,
double  edgeThreshold = 10,
double  sigma = 1.6,
bool  enable_precise_upscale = false 
)
static
Parameters
nfeaturesThe number of best features to retain. The features are ranked by their scores (measured in SIFT algorithm as the local contrast)
nOctaveLayersThe number of layers in each octave. 3 is the value used in D. Lowe paper. The number of octaves is computed automatically from the image resolution.
contrastThresholdThe contrast threshold used to filter out weak features in semi-uniform (low-contrast) regions. The larger the threshold, the less features are produced by the detector.
Note
The contrast threshold will be divided by nOctaveLayers when the filtering is applied. When nOctaveLayers is set to default and if you want to use the value used in D. Lowe paper, 0.03, set this argument to 0.09.
Parameters
edgeThresholdThe threshold used to filter out edge-like features. Note that the its meaning is different from the contrastThreshold, i.e. the larger the edgeThreshold, the less features are filtered out (more features are retained).
sigmaThe sigma of the Gaussian applied to the input image at the octave #0. If your image is captured with a weak camera with soft lenses, you might want to reduce the number.
enable_precise_upscaleWhether to enable precise upscaling in the scale pyramid, which maps index $\texttt{x}$ to $\texttt{2x}$. This prevents localization bias. The option is disabled by default.

◆ getContrastThreshold()

virtual CV_WRAP double cv::SIFT::getContrastThreshold ( ) const
pure virtual

◆ getDefaultName()

virtual CV_WRAP String cv::SIFT::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 CV_WRAP double cv::SIFT::getEdgeThreshold ( ) const
pure virtual

◆ getNFeatures()

virtual CV_WRAP int cv::SIFT::getNFeatures ( ) const
pure virtual

◆ getNOctaveLayers()

virtual CV_WRAP int cv::SIFT::getNOctaveLayers ( ) const
pure virtual

◆ getSigma()

virtual CV_WRAP double cv::SIFT::getSigma ( ) const
pure virtual

◆ setContrastThreshold()

virtual CV_WRAP void cv::SIFT::setContrastThreshold ( double  contrastThreshold)
pure virtual

◆ setEdgeThreshold()

virtual CV_WRAP void cv::SIFT::setEdgeThreshold ( double  edgeThreshold)
pure virtual

◆ setNFeatures()

virtual CV_WRAP void cv::SIFT::setNFeatures ( int  maxFeatures)
pure virtual

◆ setNOctaveLayers()

virtual CV_WRAP void cv::SIFT::setNOctaveLayers ( int  nOctaveLayers)
pure virtual

◆ setSigma()

virtual CV_WRAP void cv::SIFT::setSigma ( double  sigma)
pure virtual
The documentation for this class was generated from the following file: