cv::KeyPoint クラス

Data structure for salient point detectors. [詳解]

#include <types.hpp>

cv::xfeatures2d::Elliptic_KeyPointに継承されています。

公開メンバ関数
CV_WRAP	KeyPoint ()
	the default constructor
	KeyPoint (Point2f pt, float size, float angle=-1, float response=0, int octave=0, int class_id=-1)
CV_WRAP	KeyPoint (float x, float y, float size, float angle=-1, float response=0, int octave=0, int class_id=-1)
size_t	hash () const

静的公開メンバ関数
static CV_WRAP void	convert (const std::vector< KeyPoint > &keypoints, CV_OUT std::vector< Point2f > &points2f, const std::vector< int > &keypointIndexes=std::vector< int >())
static CV_WRAP void	convert (const std::vector< Point2f > &points2f, CV_OUT std::vector< KeyPoint > &keypoints, float size=1, float response=1, int octave=0, int class_id=-1)
static CV_WRAP float	overlap (const KeyPoint &kp1, const KeyPoint &kp2)

公開変数類
CV_PROP_RW Point2f	pt
	coordinates of the keypoints
CV_PROP_RW float	size
	diameter of the meaningful keypoint neighborhood
CV_PROP_RW float	angle
CV_PROP_RW float	response
	the response by which the most strong keypoints have been selected. Can be used for the further sorting or subsampling
CV_PROP_RW int	octave
	octave (pyramid layer) from which the keypoint has been extracted
CV_PROP_RW int	class_id
	object class (if the keypoints need to be clustered by an object they belong to)

詳解

Data structure for salient point detectors.

The class instance stores a keypoint, i.e. a point feature found by one of many available keypoint detectors, such as Harris corner detector, FAST, StarDetector, SURF, SIFT 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 KDTree or another method.

構築子と解体子

KeyPoint() [1/2]

cv::KeyPoint::KeyPoint	(	Point2f	pt,
		float	size,
		float	angle = -1,
		float	response = 0,
		int	octave = 0,
		int	class_id = -1
	)

引数

pt	x & y coordinates of the keypoint
size	keypoint diameter
angle	keypoint orientation
response	keypoint detector response on the keypoint (that is, strength of the keypoint)
octave	pyramid octave in which the keypoint has been detected
class_id	object id

KeyPoint() [2/2]

CV_WRAP cv::KeyPoint::KeyPoint	(	float	x,
		float	y,
		float	size,
		float	angle = -1,
		float	response = 0,
		int	octave = 0,
		int	class_id = -1
	)

引数

x	x-coordinate of the keypoint
y	y-coordinate of the keypoint
size	keypoint diameter
angle	keypoint orientation
response	keypoint detector response on the keypoint (that is, strength of the keypoint)
octave	pyramid octave in which the keypoint has been detected
class_id	object id

関数詳解

convert() [1/2]

static CV_WRAP void cv::KeyPoint::convert ( const std::vector< KeyPoint > &  keypoints, CV_OUT std::vector< Point2f > &  points2f, const std::vector< int > &  keypointIndexes = std::vector< int >()  )

static

This method converts vector of keypoints to vector of points or the reverse, where each keypoint is assigned the same size and the same orientation.

引数

keypoints	Keypoints obtained from any feature detection algorithm like SIFT/SURF/ORB
points2f	Array of (x,y) coordinates of each keypoint
keypointIndexes	Array of indexes of keypoints to be converted to points. (Acts like a mask to convert only specified keypoints)

convert() [2/2]

static CV_WRAP void cv::KeyPoint::convert ( const std::vector< Point2f > &  points2f, CV_OUT std::vector< KeyPoint > &  keypoints, float  size = 1, float  response = 1, int  octave = 0, int  class_id = -1  )

static

これはオーバーロードされたメンバ関数です。利便性のために用意されています。元の関数との違いは引き数のみです。

引数

points2f	Array of (x,y) coordinates of each keypoint
keypoints	Keypoints obtained from any feature detection algorithm like SIFT/SURF/ORB
size	keypoint diameter
response	keypoint detector response on the keypoint (that is, strength of the keypoint)
octave	pyramid octave in which the keypoint has been detected
class_id	object id

overlap()

static CV_WRAP float cv::KeyPoint::overlap ( const KeyPoint &  kp1, const KeyPoint &  kp2  )

static

This method computes overlap for pair of keypoints. Overlap is the ratio between area of keypoint regions' intersection and area of keypoint regions' union (considering keypoint region as circle). If they don't overlap, we get zero. If they coincide at same location with same size, we get 1.

引数

kp1	First keypoint
kp2	Second keypoint

メンバ詳解

angle

CV_PROP_RW 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.

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このクラス詳解は次のファイルから抽出されました:

• core/types.hpp