Drawing Function of Keypoints and Matches

Enumerations
enum	cv::DrawMatchesFlags {   cv::DrawMatchesFlags::DEFAULT = 0,   cv::DrawMatchesFlags::DRAW_OVER_OUTIMG = 1,   cv::DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS = 2,   cv::DrawMatchesFlags::DRAW_RICH_KEYPOINTS = 4 }

Functions
void	cv::drawKeypoints (InputArray image, const std::vector< KeyPoint > &keypoints, InputOutputArray outImage, const Scalar &color=Scalar::all(-1), DrawMatchesFlags flags=DrawMatchesFlags::DEFAULT)
	Draws keypoints. More...
void	cv::drawMatches (InputArray img1, const std::vector< KeyPoint > &keypoints1, InputArray img2, const std::vector< KeyPoint > &keypoints2, const std::vector< DMatch > &matches1to2, InputOutputArray outImg, const Scalar &matchColor=Scalar::all(-1), const Scalar &singlePointColor=Scalar::all(-1), const std::vector< char > &matchesMask=std::vector< char >(), DrawMatchesFlags flags=DrawMatchesFlags::DEFAULT)
	Draws the found matches of keypoints from two images. More...
void	cv::drawMatches (InputArray img1, const std::vector< KeyPoint > &keypoints1, InputArray img2, const std::vector< KeyPoint > &keypoints2, const std::vector< DMatch > &matches1to2, InputOutputArray outImg, const int matchesThickness, const Scalar &matchColor=Scalar::all(-1), const Scalar &singlePointColor=Scalar::all(-1), const std::vector< char > &matchesMask=std::vector< char >(), DrawMatchesFlags flags=DrawMatchesFlags::DEFAULT)
void	cv::drawMatches (InputArray img1, const std::vector< KeyPoint > &keypoints1, InputArray img2, const std::vector< KeyPoint > &keypoints2, const std::vector< std::vector< DMatch > > &matches1to2, InputOutputArray outImg, const Scalar &matchColor=Scalar::all(-1), const Scalar &singlePointColor=Scalar::all(-1), const std::vector< std::vector< char > > &matchesMask=std::vector< std::vector< char > >(), DrawMatchesFlags flags=DrawMatchesFlags::DEFAULT)

Detailed Description

Enumeration Type Documentation

DrawMatchesFlags

enum cv::DrawMatchesFlags

strong

#include <opencv2/features2d.hpp>

Enumerator
DEFAULT	Output image matrix will be created (Mat::create), i.e. existing memory of output image may be reused. Two source image, matches and single keypoints will be drawn. For each keypoint only the center point will be drawn (without the circle around keypoint with keypoint size and orientation).
DRAW_OVER_OUTIMG	Output image matrix will not be created (Mat::create). Matches will be drawn on existing content of output image.
NOT_DRAW_SINGLE_POINTS	Single keypoints will not be drawn.
DRAW_RICH_KEYPOINTS	For each keypoint the circle around keypoint with keypoint size and orientation will be drawn.

Function Documentation

drawKeypoints()

void cv::drawKeypoints	(	InputArray	image,
		const std::vector< KeyPoint > &	keypoints,
		InputOutputArray	outImage,
		const Scalar &	color = Scalar::all(-1),
		DrawMatchesFlags	flags = DrawMatchesFlags::DEFAULT
	)

Python:
	cv.drawKeypoints(	image, keypoints, outImage[, color[, flags]]	) ->	outImage

#include <opencv2/features2d.hpp>

Draws keypoints.

Parameters

image	Source image.
keypoints	Keypoints from the source image.
outImage	Output image. Its content depends on the flags value defining what is drawn in the output image. See possible flags bit values below.
color	Color of keypoints.
flags	Flags setting drawing features. Possible flags bit values are defined by DrawMatchesFlags. See details above in drawMatches .

Note

For Python API, flags are modified as cv.DRAW_MATCHES_FLAGS_DEFAULT, cv.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS, cv.DRAW_MATCHES_FLAGS_DRAW_OVER_OUTIMG, cv.DRAW_MATCHES_FLAGS_NOT_DRAW_SINGLE_POINTS

drawMatches() [1/3]

void cv::drawMatches	(	InputArray	img1,
		const std::vector< KeyPoint > &	keypoints1,
		InputArray	img2,
		const std::vector< KeyPoint > &	keypoints2,
		const std::vector< DMatch > &	matches1to2,
		InputOutputArray	outImg,
		const Scalar &	matchColor = Scalar::all(-1),
		const Scalar &	singlePointColor = Scalar::all(-1),
		const std::vector< char > &	matchesMask = std::vector< char >(),
		DrawMatchesFlags	flags = DrawMatchesFlags::DEFAULT
	)

Python:
	cv.drawMatches(	img1, keypoints1, img2, keypoints2, matches1to2, outImg[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg
	cv.drawMatches(	img1, keypoints1, img2, keypoints2, matches1to2, outImg, matchesThickness[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg
	cv.drawMatchesKnn(	img1, keypoints1, img2, keypoints2, matches1to2, outImg[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg

#include <opencv2/features2d.hpp>

Draws the found matches of keypoints from two images.

Parameters

img1	First source image.
keypoints1	Keypoints from the first source image.
img2	Second source image.
keypoints2	Keypoints from the second source image.
matches1to2	Matches from the first image to the second one, which means that keypoints1[i] has a corresponding point in keypoints2[matches[i]] .
outImg	Output image. Its content depends on the flags value defining what is drawn in the output image. See possible flags bit values below.
matchColor	Color of matches (lines and connected keypoints). If matchColor==Scalar::all(-1) , the color is generated randomly.
singlePointColor	Color of single keypoints (circles), which means that keypoints do not have the matches. If singlePointColor==Scalar::all(-1) , the color is generated randomly.
matchesMask	Mask determining which matches are drawn. If the mask is empty, all matches are drawn.
flags	Flags setting drawing features. Possible flags bit values are defined by DrawMatchesFlags.

This function draws matches of keypoints from two images in the output image. Match is a line connecting two keypoints (circles). See cv::DrawMatchesFlags.

drawMatches() [2/3]

void cv::drawMatches	(	InputArray	img1,
		const std::vector< KeyPoint > &	keypoints1,
		InputArray	img2,
		const std::vector< KeyPoint > &	keypoints2,
		const std::vector< DMatch > &	matches1to2,
		InputOutputArray	outImg,
		const int	matchesThickness,
		const Scalar &	matchColor = Scalar::all(-1),
		const Scalar &	singlePointColor = Scalar::all(-1),
		const std::vector< char > &	matchesMask = std::vector< char >(),
		DrawMatchesFlags	flags = DrawMatchesFlags::DEFAULT
	)

Python:
	cv.drawMatches(	img1, keypoints1, img2, keypoints2, matches1to2, outImg[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg
	cv.drawMatches(	img1, keypoints1, img2, keypoints2, matches1to2, outImg, matchesThickness[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg
	cv.drawMatchesKnn(	img1, keypoints1, img2, keypoints2, matches1to2, outImg[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg

#include <opencv2/features2d.hpp>

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

drawMatches() [3/3]

void cv::drawMatches	(	InputArray	img1,
		const std::vector< KeyPoint > &	keypoints1,
		InputArray	img2,
		const std::vector< KeyPoint > &	keypoints2,
		const std::vector< std::vector< DMatch > > &	matches1to2,
		InputOutputArray	outImg,
		const Scalar &	matchColor = Scalar::all(-1),
		const Scalar &	singlePointColor = Scalar::all(-1),
		const std::vector< std::vector< char > > &	matchesMask = std::vector< std::vector< char > >(),
		DrawMatchesFlags	flags = DrawMatchesFlags::DEFAULT
	)

Python:
	cv.drawMatches(	img1, keypoints1, img2, keypoints2, matches1to2, outImg[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg
	cv.drawMatches(	img1, keypoints1, img2, keypoints2, matches1to2, outImg, matchesThickness[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg
	cv.drawMatchesKnn(	img1, keypoints1, img2, keypoints2, matches1to2, outImg[, matchColor[, singlePointColor[, matchesMask[, flags]]]]	) ->	outImg

#include <opencv2/features2d.hpp>