Main class for marker detection. More...

#include <markerdetector.h>

Classes
class	MarkerCandidate

Public Types
enum	CornerRefinementMethod { NONE, HARRIS, SUBPIX, LINES }

enum	ThresholdMethods { FIXED_THRES, ADPT_THRES, CANNY }

Public Member Functions
void	detect (const cv::Mat &input, std::vector< Marker > &detectedMarkers, cv::Mat camMatrix=cv::Mat(), cv::Mat distCoeff=cv::Mat(), float markerSizeMeters=-1, bool setYPerperdicular=false) throw (cv::Exception)

void	detect (const cv::Mat &input, std::vector< Marker > &detectedMarkers, CameraParameters camParams, float markerSizeMeters=-1, bool setYPerperdicular=false) throw (cv::Exception)

void	detectRectangles (const cv::Mat &thresImg, vector< std::vector< cv::Point2f > > &candidates)

void	enableErosion (bool enable)

void	enableLockedCornersMethod (bool enable)

const vector< std::vector< cv::Point2f > > &	getCandidates ()

CornerRefinementMethod	getCornerRefinementMethod () const

int	getDesiredSpeed () const

void	getMinMaxSize (float &min, float &max)

const cv::Mat &	getThresholdedImage ()

ThresholdMethods	getThresholdMethod () const

void	getThresholdParams (double &param1, double &param2) const

int	getWarpSize () const

	MarkerDetector ()

void	pyrDown (unsigned int level)

void	refineCandidateLines (MarkerCandidate &candidate, const cv::Mat &camMatrix, const cv::Mat &distCoeff)

void	setCornerRefinementMethod (CornerRefinementMethod method)

void	setDesiredSpeed (int val)

void	setMakerDetectorFunction (int(*markerdetector_func)(const cv::Mat &in, int &nRotations))

void	setMinMaxSize (float min=0.03, float max=0.5) throw (cv::Exception)

void	setThresholdMethod (ThresholdMethods m)

void	setThresholdParamRange (size_t r1=0, size_t r2=0)

void	setThresholdParams (double param1, double param2)

void	setWarpSize (int val) throw (cv::Exception)

void	thresHold (int method, const cv::Mat &grey, cv::Mat &thresImg, double param1=-1, double param2=-1) throw (cv::Exception)

bool	warp (cv::Mat &in, cv::Mat &out, cv::Size size, std::vector< cv::Point2f > points) throw (cv::Exception)

	~MarkerDetector ()

Static Public Member Functions
static void	glGetProjectionMatrix (CameraParameters &CamMatrix, cv::Size orgImgSize, cv::Size size, double proj_matrix[16], double gnear, double gfar, bool invert=false) throw (cv::Exception)

Private Member Functions
void	detectRectangles (vector< cv::Mat > &vimages, vector< MarkerCandidate > &candidates)

void	distortPoints (vector< cv::Point2f > in, vector< cv::Point2f > &out, const cv::Mat &camMatrix, const cv::Mat &distCoeff)

void	draw (cv::Mat out, const std::vector< Marker > &markers)

void	drawAllContours (cv::Mat input, std::vector< std::vector< cv::Point > > &contours)

void	drawApproxCurve (cv::Mat &in, std::vector< cv::Point > &approxCurve, cv::Scalar color)

void	drawContour (cv::Mat &in, std::vector< cv::Point > &contour, cv::Scalar)

void	findBestCornerInRegion_harris (const cv::Mat &grey, vector< cv::Point2f > &Corners, int blockSize)

void	findCornerMaxima (vector< cv::Point2f > &Corners, const cv::Mat &grey, int wsize)

cv::Point2f	getCrossPoint (const cv::Point3f &line1, const cv::Point3f &line2)

void	interpolate2Dline (const vector< cv::Point2f > &inPoints, cv::Point3f &outLine)

bool	isInto (cv::Mat &contour, std::vector< cv::Point2f > &b)

template<typename T >
void	joinVectors (vector< vector< T > > &vv, vector< T > &v, bool clearv=false)

int	perimeter (std::vector< cv::Point2f > &a)

template<typename T >
void	removeElements (vector< T > &vinout, const vector< bool > &toRemove)

bool	warp_cylinder (cv::Mat &in, cv::Mat &out, cv::Size size, MarkerCandidate &mc) throw (cv::Exception)

Private Attributes
float	_borderDistThres

vector< std::vector< cv::Point2f > >	_candidates

CornerRefinementMethod	_cornerMethod

int	_markerWarpSize

float	_maxSize

float	_minSize

int	_speed

ThresholdMethods	_thresMethod

double	_thresParam1

double	_thresParam1_range

double	_thresParam2

bool	_useLockedCorners

cv::Mat	grey

int(*	markerIdDetector_ptrfunc )(const cv::Mat &in, int &nRotations)

cv::Mat	thres

Detailed Description

Main class for marker detection.

Definition at line 43 of file markerdetector.h.

Member Enumeration Documentation

◆ CornerRefinementMethod

enum aruco::MarkerDetector::CornerRefinementMethod

Methods for corner refinement

Enumerator
NONE
HARRIS
SUBPIX
LINES

Definition at line 162 of file markerdetector.h.

◆ ThresholdMethods

enum aruco::MarkerDetector::ThresholdMethods

This set the type of thresholding methods available

Enumerator
FIXED_THRES
ADPT_THRES
CANNY

Definition at line 103 of file markerdetector.h.

Constructor & Destructor Documentation

◆ MarkerDetector()

aruco::MarkerDetector::MarkerDetector ( )

See

Definition at line 50 of file markerdetector.cpp.

◆ ~MarkerDetector()

aruco::MarkerDetector::~MarkerDetector ( )

Definition at line 72 of file markerdetector.cpp.

Member Function Documentation

◆ detect() [1/2]

void aruco::MarkerDetector::detect	(	const cv::Mat &	input,
		std::vector< Marker > &	detectedMarkers,
		cv::Mat	camMatrix = `cv::Mat()`,
		cv::Mat	distCoeff = `cv::Mat()`,
		float	markerSizeMeters = `-1`,
		bool	setYPerperdicular = `false`
	)
throw	(	cv::Exception
	)

Detects the markers in the image passed

If you provide information about the camera parameters and the size of the marker, then, the extrinsics of the markers are detected

Parameters

input	input color image
detectedMarkers	output vector with the markers detected
camMatrix	intrinsic camera information.
distCoeff	camera distorsion coefficient. If set Mat() if is assumed no camera distorion
markerSizeMeters	size of the marker sides expressed in meters
setYPerperdicular	If set the Y axis will be perpendicular to the surface. Otherwise, it will be the Z axis

◆ detect() [2/2]

void aruco::MarkerDetector::detect	(	const cv::Mat &	input,
		std::vector< Marker > &	detectedMarkers,
		CameraParameters	camParams,
		float	markerSizeMeters = `-1`,
		bool	setYPerperdicular = `false`
	)
throw	(	cv::Exception
	)

Detects the markers in the image passed

If you provide information about the camera parameters and the size of the marker, then, the extrinsics of the markers are detected

Parameters

input	input color image
detectedMarkers	output vector with the markers detected
camParams	Camera parameters
markerSizeMeters	size of the marker sides expressed in meters
setYPerperdicular	If set the Y axis will be perpendicular to the surface. Otherwise, it will be the Z axis

Definition at line 108 of file markerdetector.cpp.

◆ detectRectangles() [1/2]

void aruco::MarkerDetector::detectRectangles	(	const cv::Mat &	thresImg,
		vector< std::vector< cv::Point2f > > &	candidates
	)

Detection of candidates to be markers, i.e., rectangles. This function returns in candidates all the rectangles found in a thresolded image

Definition at line 261 of file markerdetector.cpp.

◆ detectRectangles() [2/2]

void aruco::MarkerDetector::detectRectangles	(	vector< cv::Mat > &	vimages,
		vector< MarkerCandidate > &	candidates
	)

private

Detection of candidates to be markers, i.e., rectangles. This function returns in candidates all the rectangles found in a thresolded image

for each contour, analyze if it is a paralelepiped likely to be the marker

sort the points in anti-clockwise order

remove these elements which corners are too close to each other

Definition at line 272 of file markerdetector.cpp.

◆ distortPoints()

void aruco::MarkerDetector::distortPoints	(	vector< cv::Point2f >	in,
		vector< cv::Point2f > &	out,
		const cv::Mat &	camMatrix,
		const cv::Mat &	distCoeff
	)

private

Definition at line 914 of file markerdetector.cpp.

◆ draw()

void aruco::MarkerDetector::draw	(	cv::Mat	out,
		const std::vector< Marker > &	markers
	)

private

Definition at line 961 of file markerdetector.cpp.

◆ drawAllContours()

void aruco::MarkerDetector::drawAllContours	(	cv::Mat	input,
		std::vector< std::vector< cv::Point > > &	contours
	)

private

Definition at line 935 of file markerdetector.cpp.

◆ drawApproxCurve()

void aruco::MarkerDetector::drawApproxCurve	(	cv::Mat &	in,
		std::vector< cv::Point > &	approxCurve,
		cv::Scalar	color
	)

private

Definition at line 949 of file markerdetector.cpp.

◆ drawContour()

void aruco::MarkerDetector::drawContour	(	cv::Mat &	in,
		std::vector< cv::Point > &	contour,
		cv::Scalar
	)

private

Definition at line 943 of file markerdetector.cpp.

◆ enableErosion()

void aruco::MarkerDetector::enableErosion ( bool enable )

inline

Deprecated!!!

Enables/Disables erosion process that is REQUIRED for chessboard like boards. By default, this property is enabled

Definition at line 192 of file markerdetector.h.

◆ enableLockedCornersMethod()

void aruco::MarkerDetector::enableLockedCornersMethod ( bool enable )

This method assumes that the markers may have some of its corners joined either to another marker in a chessboard like pattern) or to a rectangle. This is the case in which the subpixel refinement method in opencv work best.

Enabling this does not force you to use locked corners, normals markers will be detected also. However, when using locked corners, enabling this option will increase robustness in detection at the cost of higher computational time. , Note for developer: Enabling this option forces a call to findCornerMaxima

Definition at line 117 of file markerdetector.cpp.

◆ findBestCornerInRegion_harris()

void aruco::MarkerDetector::findBestCornerInRegion_harris	(	const cv::Mat &	grey,
		vector< cv::Point2f > &	Corners,
		int	blockSize
	)

private

Definition at line 754 of file markerdetector.cpp.

◆ findCornerMaxima()

void aruco::MarkerDetector::findCornerMaxima	(	vector< cv::Point2f > &	Corners,
		const cv::Mat &	grey,
		int	wsize
	)

private

Definition at line 1040 of file markerdetector.cpp.

◆ getCandidates()

const vector< std::vector< cv::Point2f > >& aruco::MarkerDetector::getCandidates ( )

inline

Returns a list candidates to be markers (rectangles), for which no valid id was found after calling detectRectangles

Definition at line 261 of file markerdetector.h.

◆ getCornerRefinementMethod()

CornerRefinementMethod aruco::MarkerDetector::getCornerRefinementMethod ( ) const

inline

Definition at line 168 of file markerdetector.h.

◆ getCrossPoint()

Point2f aruco::MarkerDetector::getCrossPoint	(	const cv::Point3f &	line1,
		const cv::Point3f &	line2
	)

private

Definition at line 891 of file markerdetector.cpp.

◆ getDesiredSpeed()

int aruco::MarkerDetector::getDesiredSpeed ( ) const

inline

Definition at line 204 of file markerdetector.h.

◆ getMinMaxSize()

void aruco::MarkerDetector::getMinMaxSize	(	float &	min,
		float &	max
	)

inline

reads the min and max sizes employed

Parameters

min	output size of the contour to consider a possible marker as valid (0,1]
max	output size of the contour to consider a possible marker as valid [0,1)

Definition at line 182 of file markerdetector.h.

◆ getThresholdedImage()

const cv::Mat& aruco::MarkerDetector::getThresholdedImage ( )

inline

Returns a reference to the internal image thresholded. It is for visualization purposes and to adjust manually the parameters

Definition at line 159 of file markerdetector.h.

◆ getThresholdMethod()

ThresholdMethods aruco::MarkerDetector::getThresholdMethod ( ) const

inline

Returns the current threshold method

Definition at line 112 of file markerdetector.h.

◆ getThresholdParams()

void aruco::MarkerDetector::getThresholdParams	(	double &	param1,
		double &	param2
	)		const

inline

Set the parameters of the threshold method We are currently using the Adptive threshold ee opencv doc of adaptiveThreshold for more info param1: blockSize of the pixel neighborhood that is used to calculate a threshold value for the pixel param2: The constant subtracted from the mean or weighted mean

Definition at line 150 of file markerdetector.h.

◆ getWarpSize()

int aruco::MarkerDetector::getWarpSize ( ) const

inline

Definition at line 214 of file markerdetector.h.

◆ glGetProjectionMatrix()

void aruco::MarkerDetector::glGetProjectionMatrix	(	CameraParameters &	CamMatrix,
		cv::Size	orgImgSize,
		cv::Size	size,
		double	proj_matrix[16],
		double	gnear,
		double	gfar,
		bool	invert = `false`
	)
throw	(	cv::Exception
	)

static

DEPRECATED!!! Use the member function in CameraParameters

Given the intrinsic camera parameters returns the GL_PROJECTION matrix for opengl. PLease NOTE that when using OpenGL, it is assumed no camera distorsion! So, if it is not true, you should have undistor image

Parameters

CamMatrix	arameters of the camera specified.
orgImgSize	size of the original image
size	of the image/window where to render (can be different from the real camera image). Please not that it must be related to CamMatrix
proj_matrix	output projection matrix to give to opengl
gnear,gfar	visible rendering range
invert	indicates if the output projection matrix has to yield a horizontally inverted image because image data has not been stored in the order of glDrawPixels: bottom-to-top.

Definition at line 1001 of file markerdetector.cpp.

◆ interpolate2Dline()

void aruco::MarkerDetector::interpolate2Dline	(	const vector< cv::Point2f > &	inPoints,
		cv::Point3f &	outLine
	)

private

Definition at line 837 of file markerdetector.cpp.

◆ isInto()

bool aruco::MarkerDetector::isInto	(	cv::Mat &	contour,
		std::vector< cv::Point2f > &	b
	)

private

Definition at line 727 of file markerdetector.cpp.

◆ joinVectors()

template<typename T >

void aruco::MarkerDetector::joinVectors	(	vector< vector< T > > &	vv,
		vector< T > &	v,
		bool	clearv = `false`
	)

inlineprivate

Definition at line 383 of file markerdetector.h.

◆ perimeter()

int aruco::MarkerDetector::perimeter ( std::vector< cv::Point2f > & a )

private

Definition at line 740 of file markerdetector.cpp.

◆ pyrDown()

void aruco::MarkerDetector::pyrDown ( unsigned int level )

inline

Deprecated

Use an smaller version of the input image for marker detection. If your marker is small enough, you can employ an smaller image to perform the detection without noticeable reduction in the precision. Internally, we are performing a pyrdown operation

Parameters

level number of times the image size is divided by 2. Internally, we are performing a pyrdown.

Definition at line 242 of file markerdetector.h.

◆ refineCandidateLines()

void aruco::MarkerDetector::refineCandidateLines	(	MarkerDetector::MarkerCandidate &	candidate,
		const cv::Mat &	camMatrix,
		const cv::Mat &	distCoeff
	)

Refine MarkerCandidate Corner using LINES method

Parameters

candidate candidate to refine corners

Definition at line 764 of file markerdetector.cpp.

◆ removeElements()

template<typename T >

void aruco::MarkerDetector::removeElements	(	vector< T > &	vinout,
		const vector< bool > &	toRemove
	)

inlineprivate

Given a vector vinout with elements and a boolean vector indicating the lements from it to remove, this function remove the elements

Parameters

vinout
toRemove

Definition at line 359 of file markerdetector.h.

◆ setCornerRefinementMethod()

void aruco::MarkerDetector::setCornerRefinementMethod ( CornerRefinementMethod method )

inline

Definition at line 165 of file markerdetector.h.

◆ setDesiredSpeed()

void aruco::MarkerDetector::setDesiredSpeed ( int val )

Specifies a value to indicate the required speed for the internal processes. If you need maximum speed (at the cost of a lower detection rate), use the value 3, If you rather a more precise and slow detection, set it to 0.

Actually, the main differences are that in highspeed mode, we employ setCornerRefinementMethod(NONE) and internally, we use a small canonical image to detect the marker. In low speed mode, we use setCornerRefinementMethod(HARRIS) and a bigger size for the canonical marker image

Definition at line 80 of file markerdetector.cpp.

◆ setMakerDetectorFunction()

void aruco::MarkerDetector::setMakerDetectorFunction ( int(*)(const cv::Mat &in, int &nRotations) markerdetector_func )

inline

Allows to specify the function that identifies a marker. Therefore, you can create your own type of markers different from these employed by default in the library. The marker function must have the following structure:

int myMarkerIdentifier(const cv::Mat &in,int &nRotations);

The marker function receives the image 'in' with the region that migh contain one of your markers. These are the rectangular regions with black in the image.

As output your marker function must indicate the following information. First, the output parameter nRotations must indicate how many times the marker must be rotated clockwise 90 deg to be in its ideal position. (The way you would see it when you print it). This is employed to know always which is the corner that acts as reference system. Second, the function must return -1 if the image does not contains one of your markers, and its id otherwise.

Definition at line 232 of file markerdetector.h.

◆ setMinMaxSize()

void aruco::MarkerDetector::setMinMaxSize	(	float	min = `0.03`,
		float	max = `0.5`
	)
throw	(	cv::Exception
	)

Specifies the min and max sizes of the markers as a fraction of the image size. By size we mean the maximum of cols and rows.

Parameters

min	size of the contour to consider a possible marker as valid (0,1]
max	size of the contour to consider a possible marker as valid [0,1)

Definition at line 1015 of file markerdetector.cpp.

◆ setThresholdMethod()

void aruco::MarkerDetector::setThresholdMethod ( ThresholdMethods m )

inline

Sets the threshold method

Definition at line 109 of file markerdetector.h.

◆ setThresholdParamRange()

void aruco::MarkerDetector::setThresholdParamRange	(	size_t	r1 = `0`,
		size_t	r2 = `0`
	)

inline

Allows for a parallel search of several values of the param1 simultaneously (in different threads) The param r1 the indicates how many values around the current value of param1 are evaluated. In other words if r1>0, param1 is searched in range [param1- r1 ,param1+ r1 ]

r2 unused yet. Added in case of future need.

Definition at line 130 of file markerdetector.h.

◆ setThresholdParams()

void aruco::MarkerDetector::setThresholdParams	(	double	param1,
		double	param2
	)

inline

Set the parameters of the threshold method We are currently using the Adptive threshold ee opencv doc of adaptiveThreshold for more info

Parameters

param1	blockSize of the pixel neighborhood that is used to calculate a threshold value for the pixel
param2	The constant subtracted from the mean or weighted mean

Definition at line 119 of file markerdetector.h.

◆ setWarpSize()

void aruco::MarkerDetector::setWarpSize	(	int	val	)
throw	(	cv::Exception
	)

Specifies the size for the canonical marker image. A big value makes the detection slower than a small value. Minimun value is 10. Default value is 56.

Definition at line 1033 of file markerdetector.cpp.

◆ thresHold()

void aruco::MarkerDetector::thresHold	(	int	method,
		const cv::Mat &	grey,
		cv::Mat &	thresImg,
		double	param1 = `-1`,
		double	param2 = `-1`
	)
throw	(	cv::Exception
	)

Methods you may not need

Thesde methods do the hard work. They have been set public in case you want to do customizations

Thesholds the passed image with the specified method.

Definition at line 422 of file markerdetector.cpp.

◆ warp()

bool aruco::MarkerDetector::warp	(	cv::Mat &	in,
		cv::Mat &	out,
		cv::Size	size,
		std::vector< cv::Point2f >	points
	)
throw	(	cv::Exception
	)

Given the iput image with markers, creates an output image with it in the canonical position

Parameters

in	input image
out	image with the marker
size	of out
points	4 corners of the marker in the image in

Returns: true if the operation succeed

Definition at line 464 of file markerdetector.cpp.

◆ warp_cylinder()

bool aruco::MarkerDetector::warp_cylinder	(	cv::Mat &	in,
		cv::Mat &	out,
		cv::Size	size,
		MarkerCandidate &	mc
	)
throw	(	cv::Exception
	)

private

Definition at line 579 of file markerdetector.cpp.

Member Data Documentation

◆ _borderDistThres

float aruco::MarkerDetector::_borderDistThres

private

Definition at line 319 of file markerdetector.h.

◆ _candidates

vector< std::vector< cv::Point2f > > aruco::MarkerDetector::_candidates

private

Definition at line 321 of file markerdetector.h.

◆ _cornerMethod

CornerRefinementMethod aruco::MarkerDetector::_cornerMethod

private

Definition at line 309 of file markerdetector.h.

◆ _markerWarpSize

int aruco::MarkerDetector::_markerWarpSize

private

Definition at line 318 of file markerdetector.h.

◆ _maxSize

float aruco::MarkerDetector::_maxSize

private

Definition at line 311 of file markerdetector.h.

◆ _minSize

float aruco::MarkerDetector::_minSize

private

Definition at line 311 of file markerdetector.h.

◆ _speed

int aruco::MarkerDetector::_speed

private

Definition at line 317 of file markerdetector.h.

◆ _thresMethod

ThresholdMethods aruco::MarkerDetector::_thresMethod

private

Definition at line 305 of file markerdetector.h.

◆ _thresParam1

double aruco::MarkerDetector::_thresParam1

private

Definition at line 307 of file markerdetector.h.

◆ _thresParam1_range

double aruco::MarkerDetector::_thresParam1_range

private

Definition at line 307 of file markerdetector.h.

◆ _thresParam2

double aruco::MarkerDetector::_thresParam2

private

Definition at line 307 of file markerdetector.h.

◆ _useLockedCorners

bool aruco::MarkerDetector::_useLockedCorners

private

Definition at line 314 of file markerdetector.h.

◆ grey

cv::Mat aruco::MarkerDetector::grey

private

Definition at line 323 of file markerdetector.h.

◆ markerIdDetector_ptrfunc

int(* aruco::MarkerDetector::markerIdDetector_ptrfunc) (const cv::Mat &in, int &nRotations)

private

Definition at line 325 of file markerdetector.h.

◆ thres

cv::Mat aruco::MarkerDetector::thres

private

Definition at line 323 of file markerdetector.h.

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

Classes

Public Types

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Member Enumeration Documentation

◆ CornerRefinementMethod

◆ ThresholdMethods

Constructor & Destructor Documentation

◆ MarkerDetector()

◆ ~MarkerDetector()

Member Function Documentation

◆ detect() [1/2]

◆ detect() [2/2]

◆ detectRectangles() [1/2]

◆ detectRectangles() [2/2]

◆ distortPoints()

◆ draw()

◆ drawAllContours()

◆ drawApproxCurve()

◆ drawContour()

◆ enableErosion()

◆ enableLockedCornersMethod()

◆ findBestCornerInRegion_harris()

◆ findCornerMaxima()

◆ getCandidates()

◆ getCornerRefinementMethod()

◆ getCrossPoint()

◆ getDesiredSpeed()

◆ getMinMaxSize()

◆ getThresholdedImage()

◆ getThresholdMethod()

◆ getThresholdParams()

◆ getWarpSize()

◆ glGetProjectionMatrix()

◆ interpolate2Dline()

◆ isInto()

◆ joinVectors()

◆ perimeter()

◆ pyrDown()

◆ refineCandidateLines()

◆ removeElements()

◆ setCornerRefinementMethod()

◆ setDesiredSpeed()

◆ setMakerDetectorFunction()

◆ setMinMaxSize()

◆ setThresholdMethod()

◆ setThresholdParamRange()

◆ setThresholdParams()

◆ setWarpSize()

◆ thresHold()

Thesde methods do the hard work. They have been set public in case you want to do customizations

◆ warp()

◆ warp_cylinder()

Member Data Documentation

◆ _borderDistThres

◆ _candidates

◆ _cornerMethod

◆ _markerWarpSize

◆ _maxSize

◆ _minSize

◆ _speed

◆ _thresMethod

◆ _thresParam1

◆ _thresParam1_range

◆ _thresParam2

◆ _useLockedCorners

◆ grey

◆ markerIdDetector_ptrfunc

◆ thres