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 setYPerpendicular=true) throw (cv::Exception)
void	detect (const cv::Mat &input, std::vector< Marker > &detectedMarkers, CameraParameters camParams, float markerSizeMeters=-1, bool setYPerpendicular=true) throw (cv::Exception)
void	detectRectangles (const cv::Mat &thresImg, vector< std::vector< cv::Point2f > > &candidates)
void	enableErosion (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
	MarkerDetector ()
void	pyrDown (unsigned int level)
void	refineCandidateLines (MarkerCandidate &candidate)
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	setThresholdParams (double param1, double param2)
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 (const cv::Mat &thresImg, vector< MarkerCandidate > &candidates)
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)
cv::Point2f	getCrossPoint (const cv::Point3f &line1, const cv::Point3f &line2)
void	interpolate2Dline (const vector< cv::Point > &inPoints, cv::Point3f &outLine)
bool	isInto (cv::Mat &contour, std::vector< cv::Point2f > &b)
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
vector< std::vector < cv::Point2f > >	_candidates
CornerRefinementMethod	_cornerMethod
bool	_doErosion
bool	_enableCylinderWarp
int	_markerWarpSize
float	_maxSize
float	_minSize
int	_speed
ThresholdMethods	_thresMethod
double	_thresParam1
double	_thresParam2
cv::Mat	grey
int(*	markerIdDetector_ptrfunc )(const cv::Mat &in, int &nRotations)
int	pyrdown_level
cv::Mat	reduced
cv::Mat	thres
cv::Mat	thres2

Detailed Description

Main class for marker detection.

Definition at line 44 of file markerdetector.h.

Member Enumeration Documentation

enum aruco::MarkerDetector::CornerRefinementMethod

Methods for corner refinement

Enumerator:

NONE
HARRIS
SUBPIX
LINES

Definition at line 144 of file markerdetector.h.

enum aruco::MarkerDetector::ThresholdMethods

This set the type of thresholding methods available

Enumerator:

FIXED_THRES
ADPT_THRES
CANNY

Definition at line 100 of file markerdetector.h.

Constructor & Destructor Documentation

aruco::MarkerDetector::MarkerDetector ( )

See

Definition at line 46 of file markerdetector.cpp.

aruco::MarkerDetector::~MarkerDetector ( )

Definition at line 67 of file markerdetector.cpp.

Member Function Documentation

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	setYPerpendicular = `true`
	)		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
setYPerpendicular	If set the Y axis will be perpendicular to the surface. Otherwise, it will be the Z axis

void aruco::MarkerDetector::detect	(	const cv::Mat &	input,
		std::vector< Marker > &	detectedMarkers,
		CameraParameters	camParams,
		float	markerSizeMeters = `-1`,
		bool	setYPerpendicular = `true`
	)		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
setYPerpendicular	If set the Y axis will be perpendicular to the surface. Otherwise, it will be the Z axis

Definition at line 107 of file markerdetector.cpp.

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.

void aruco::MarkerDetector::detectRectangles	(	const cv::Mat &	thresImg,
		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 whise corners are too close to each other

Definition at line 271 of file markerdetector.cpp.

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

Definition at line 942 of file markerdetector.cpp.

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

Definition at line 909 of file markerdetector.cpp.

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

Definition at line 928 of file markerdetector.cpp.

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

Definition at line 920 of file markerdetector.cpp.

void aruco::MarkerDetector::enableErosion ( bool enable ) [inline]

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

Definition at line 173 of file markerdetector.h.

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

Definition at line 725 of file markerdetector.cpp.

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 233 of file markerdetector.h.

CornerRefinementMethod aruco::MarkerDetector::getCornerRefinementMethod ( ) const [inline]

Definition at line 152 of file markerdetector.h.

Point2f aruco::MarkerDetector::getCrossPoint	(	const cv::Point3f &	line1,
		const cv::Point3f &	line2
	)		`[private]`

Definition at line 874 of file markerdetector.cpp.

int aruco::MarkerDetector::getDesiredSpeed ( ) const [inline]

Definition at line 185 of file markerdetector.h.

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 168 of file markerdetector.h.

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 139 of file markerdetector.h.

ThresholdMethods aruco::MarkerDetector::getThresholdMethod ( ) const [inline]

Returns the current threshold method

Definition at line 111 of file markerdetector.h.

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 130 of file markerdetector.h.

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 984 of file markerdetector.cpp.

void aruco::MarkerDetector::interpolate2Dline	(	const vector< cv::Point > &	inPoints,
		cv::Point3f &	outLine
	)		`[private]`

Definition at line 819 of file markerdetector.cpp.

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

Definition at line 696 of file markerdetector.cpp.

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

Definition at line 709 of file markerdetector.cpp.

void aruco::MarkerDetector::pyrDown ( unsigned int level ) [inline]

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 214 of file markerdetector.h.

void aruco::MarkerDetector::refineCandidateLines ( MarkerDetector::MarkerCandidate & candidate )

Refine MarkerCandidate Corner using LINES method

Parameters:

candidate candidate to refine corners

Definition at line 761 of file markerdetector.cpp.

template<typename T >

void aruco::MarkerDetector::removeElements	(	vector< T > &	vinout,
		const vector< bool > &	toRemove
	)		`[inline, private]`

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 331 of file markerdetector.h.

void aruco::MarkerDetector::setCornerRefinementMethod ( CornerRefinementMethod method ) [inline]

Definition at line 147 of file markerdetector.h.

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 78 of file markerdetector.cpp.

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 204 of file markerdetector.h.

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 998 of file markerdetector.cpp.

void aruco::MarkerDetector::setThresholdMethod ( ThresholdMethods m ) [inline]

Sets the threshold method

Definition at line 106 of file markerdetector.h.

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 120 of file markerdetector.h.

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 411 of file markerdetector.cpp.