#include <features2d.hpp>
Public Member Functions | |
KeyPoint () | |
the default constructor More... | |
KeyPoint (Point2f _pt, float _size, float _angle=-1, float _response=0, int _octave=0, int _class_id=-1) | |
the full constructor More... | |
KeyPoint (float x, float y, float _size, float _angle=-1, float _response=0, int _octave=0, int _class_id=-1) | |
another form of the full constructor More... | |
size_t | hash () const |
Static Public Member Functions | |
static void | convert (const vector< KeyPoint > &keypoints, CV_OUT vector< Point2f > &points2f, const vector< int > &keypointIndexes=vector< int >()) |
converts vector of keypoints to vector of points More... | |
static void | convert (const vector< Point2f > &points2f, CV_OUT vector< KeyPoint > &keypoints, float size=1, float response=1, int octave=0, int class_id=-1) |
converts vector of points to the vector of keypoints, where each keypoint is assigned the same size and the same orientation More... | |
static float | overlap (const KeyPoint &kp1, const KeyPoint &kp2) |
Public Attributes | |
Point2f | pt |
coordinates of the keypoints More... | |
float | size |
diameter of the meaningful keypoint neighborhood More... | |
float | angle |
float | response |
the response by which the most strong keypoints have been selected. Can be used for the further sorting or subsampling More... | |
int | octave |
octave (pyramid layer) from which the keypoint has been extracted More... | |
int | class_id |
object class (if the keypoints need to be clustered by an object they belong to) More... | |
The Keypoint Class
The class instance stores a keypoint, i.e. a point feature found by one of many available keypoint detectors, such as Harris corner detector, cv::FAST, cv::StarDetector, cv::SURF, cv::SIFT, cv::LDetector etc.
The keypoint is characterized by the 2D position, scale (proportional to the diameter of the neighborhood that needs to be taken into account), orientation and some other parameters. The keypoint neighborhood is then analyzed by another algorithm that builds a descriptor (usually represented as a feature vector). The keypoints representing the same object in different images can then be matched using cv::KDTree or another method.
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inline |
the default constructor
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inline |
the full constructor
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inline |
another form of the full constructor
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static |
converts vector of keypoints to vector of points
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static |
converts vector of points to the vector of keypoints, where each keypoint is assigned the same size and the same orientation
size_t cv::KeyPoint::hash | ( | ) | const |
computes overlap for pair of keypoints; overlap is a ratio between area of keypoint regions intersection and area of keypoint regions union (now keypoint region is circle)
float cv::KeyPoint::angle |
computed orientation of the keypoint (-1 if not applicable); it's in [0,360) degrees and measured relative to image coordinate system, ie in clockwise.
int cv::KeyPoint::class_id |
object class (if the keypoints need to be clustered by an object they belong to)
int cv::KeyPoint::octave |
octave (pyramid layer) from which the keypoint has been extracted
Point2f cv::KeyPoint::pt |
coordinates of the keypoints
float cv::KeyPoint::response |
the response by which the most strong keypoints have been selected. Can be used for the further sorting or subsampling
float cv::KeyPoint::size |
diameter of the meaningful keypoint neighborhood