#include <visp3/imgproc/vpCircleHoughTransform.h>

Classes
class	vpCircleHoughTransformParameters

Public Member Functions
	vpCircleHoughTransform ()

	vpCircleHoughTransform (const vpCircleHoughTransformParameters &algoParams)

virtual	~vpCircleHoughTransform ()

Detection methods
virtual std::vector< vpImageCircle >	detect (const vpImage< vpRGBa > &I)

virtual std::vector< vpImageCircle >	detect (const vpImage< unsigned char > &I)

virtual std::vector< vpImageCircle >	detect (const vpImage< unsigned char > &I, const int &nbCircles)

void	computeVotingMask (const vpImage< unsigned char > &I, const std::vector< vpImageCircle > &detections, std::optional< vpImage< bool > > &mask, std::optional< std::vector< std::vector< std::pair< unsigned int, unsigned int >>>> &opt_votingPoints) const

Setters
void	init (const vpCircleHoughTransformParameters &algoParams)

void	setFilteringAndGradientType (const vpImageFilter::vpCannyFilteringAndGradientType &type)

void	setGaussianParameters (const int &kernelSize, const float &stdev)

void	setGradientFilterAperture (const unsigned int &apertureSize)

void	setCannyBackend (const vpImageFilter::vpCannyBackendType &type)

void	setCannyThreshold (const float &lowerCannyThreshold, const float &upperCannyThreshold)

void	setCannyThresholdRatio (const float &lowerThreshRatio, const float &upperThreshRatio)

void	setCircleCenterMinDist (const float &center_min_dist)

void	setCircleCenterBoundingBox (const int &center_min_x, const int &center_max_x, const int &center_min_y, const int &center_max_y)

void	setCircleMinRadius (const float &circle_min_radius)

void	setCircleMaxRadius (const float &circle_max_radius)

void	setCirclePerfectness (const float &circle_perfectness)

void	setCenterComputationParameters (const int &dilatationSize, const float &centerThresh, const int &averagingWindowSize=5, const int expectedNbCenters=-1)

void	setRadiusRatioThreshold (const float &radiusRatioThresh)

void	setRadiusMergingThresholds (const float &radiusDifferenceThresh)

void	setMask (const vpImage< bool > &mask)

Getters
static const unsigned char	edgeMapOn = 255

static const unsigned char	edgeMapOff = 0

vpCircleHoughTransformParameters	m_algoParams

vpArray2D< float >	m_fg

const vpImage< bool > *	mp_mask

vpArray2D< float >	m_gradientFilterX

vpArray2D< float >	m_gradientFilterY

vpImage< float >	m_dIx

vpImage< float >	m_dIy

vpCannyEdgeDetection	m_cannyVisp

vpImage< unsigned char >	m_edgeMap

std::vector< std::pair< unsigned int, unsigned int > >	m_edgePointsList

std::vector< std::pair< float, float > >	m_centerCandidatesList

std::vector< int >	m_centerVotes

std::vector< vpImageCircle >	m_circleCandidates

std::vector< float >	m_circleCandidatesProbabilities

std::vector< unsigned int >	m_circleCandidatesVotes

std::vector< std::vector< std::pair< unsigned int, unsigned int > > >	m_circleCandidatesVotingPoints

std::vector< vpImageCircle >	m_finalCircles

std::vector< float >	m_finalCirclesProbabilities

std::vector< unsigned int >	m_finalCircleVotes

std::vector< std::vector< std::pair< unsigned int, unsigned int > > >	m_finalCirclesVotingPoints

std::vector< std::pair< float, float > >	getCenterCandidatesList () const

std::vector< int >	getCenterCandidatesVotes () const

std::vector< vpImageCircle >	getCircleCandidates () const

std::vector< float >	getCircleCandidatesProbabilities () const

std::vector< unsigned int >	getCircleCandidatesVotes () const

vpImage< float >	getGradientX () const

vpImage< float >	getGradientY () const

vpImage< unsigned char >	getEdgeMap () const

float	getCannyThreshold () const

float	getCircleCenterMinDist () const

float	getCircleMinRadius () const

float	getCircleMaxRadius () const

std::vector< float >	getDetectionsProbabilities () const

std::vector< unsigned int >	getDetectionsVotes () const

std::string	toString () const

VISP_EXPORT std::ostream &	operator<< (std::ostream &os, const vpCircleHoughTransform &detector)

virtual void	initGaussianFilters ()

virtual void	initGradientFilters ()

virtual void	computeGradients (const vpImage< unsigned char > &I)

virtual void	edgeDetection (const vpImage< unsigned char > &I)

virtual void	filterEdgeMap ()

virtual void	computeCenterCandidates ()

virtual float	computeCircleProbability (const vpImageCircle &circle, const unsigned int &nbVotes)

virtual void	computeCircleCandidates ()

virtual void	mergeCircleCandidates ()

virtual void	mergeCandidates (std::vector< vpImageCircle > &circleCandidates, std::vector< unsigned int > &circleCandidatesVotes, std::vector< float > &circleCandidatesProba, std::vector< std::vector< std::pair< unsigned int, unsigned int > > > &votingPoints)

Configuration from files
	vpCircleHoughTransform (const std::string &jsonPath)

virtual void	initFromJSON (const std::string &jsonPath)

virtual void	saveConfigurationInJSON (const std::string &jsonPath) const

void	from_json (const nlohmann::json &j, vpCircleHoughTransform &detector)

void	to_json (nlohmann::json &j, const vpCircleHoughTransform &detector)

Detailed Description

Class that permits to detect 2D circles in a image using the gradient-based Circle Hough transform. Please find more information on the algorithm here

Examples: tutorial-circle-hough.cpp.

Definition at line 62 of file vpCircleHoughTransform.h.

Constructor & Destructor Documentation

◆ vpCircleHoughTransform() [1/3]

vpCircleHoughTransform::vpCircleHoughTransform ( )

Construct a new vpCircleHoughTransform object with default parameters.

Definition at line 98 of file vpCircleHoughTransform.cpp.

References initGaussianFilters(), and initGradientFilters().

◆ vpCircleHoughTransform() [2/3]

vpCircleHoughTransform::vpCircleHoughTransform ( const vpCircleHoughTransformParameters & algoParams )

Construct a new vpCircleHoughTransform object from a vpCircleHoughTransformParameters object.

Parameters

[in] algoParams The parameters of the Circle Hough Transform.

Definition at line 106 of file vpCircleHoughTransform.cpp.

References initGaussianFilters(), and initGradientFilters().

◆ ~vpCircleHoughTransform()

vpCircleHoughTransform::~vpCircleHoughTransform ( )

virtual

Destroy the vp Circle Hough Transform object.

Definition at line 122 of file vpCircleHoughTransform.cpp.

◆ vpCircleHoughTransform() [3/3]

vpCircleHoughTransform::vpCircleHoughTransform ( const std::string & jsonPath )

Construct a new vpCircleHoughTransform object configured according to the JSON file whose path is jsonPath. Throw a vpException error if the file does not exist.

Parameters

[in] jsonPath The path towards the JSON configuration file.

Definition at line 128 of file vpCircleHoughTransform.cpp.

References initFromJSON().

Member Function Documentation

◆ computeCenterCandidates()

void vpCircleHoughTransform::computeCenterCandidates ( )

protectedvirtual

Determine the image points that are circle center candidates. Increment the center accumulator based on the edge points and gradient information. Perform thresholding to keep only the center candidates that exceed the threshold.

< Votes for the center candidates.

Definition at line 547 of file vpCircleHoughTransform.cpp.

References vpException::badValue, vpImageMorphology::dilatation(), vpException::dimensionError, edgeMapOn, vpMath::equal(), vpImage< Type >::getCols(), vpImage< Type >::getRows(), m_algoParams, m_centerCandidatesList, m_centerVotes, m_dIx, m_dIy, m_edgeMap, and m_edgePointsList.

Referenced by detect().

◆ computeCircleCandidates()

void vpCircleHoughTransform::computeCircleCandidates ( )

protectedvirtual

For each center candidate CeC_i, do:

For each edge point EP_j, compute the distance d_ij = distance(CeC_i; EP_j)
Determine to which radius candidate bin RCB_k the distance d_ij belongs to
Increment the radius candidate accumulator accum_rc[CeC_i][RCB_k]
If accum_rc[CeC_i][RCB_k] > radius_count_thresh, add the circle candidate (CeC_i, RCB_k) to the list of circle candidates

Definition at line 875 of file vpCircleHoughTransform.cpp.

References computeCircleProbability(), m_algoParams, m_centerCandidatesList, m_circleCandidates, m_circleCandidatesProbabilities, m_circleCandidatesVotes, m_circleCandidatesVotingPoints, m_dIx, m_dIy, and m_edgePointsList.

Referenced by detect().

◆ computeCircleProbability()

float vpCircleHoughTransform::computeCircleProbability	(	const vpImageCircle &	circle,
		const unsigned int &	nbVotes
	)

protectedvirtual

Compute the probability of circle given the number of pixels voting for it nbVotes. The probability is defined as the ratio of nbVotes by the theoretical number of pixel that should be visible in the image.

Parameters

circle	The circle for which we want to evaluate the probability.
nbVotes	The number of visible pixels of the given circle.

Returns: float The probability of the circle.

Definition at line 1082 of file vpCircleHoughTransform.cpp.

References vpImageCircle::computeArcLengthInRoI(), vpImageCircle::computePixelsInMask(), vpImage< Type >::getHeight(), vpImage< Type >::getWidth(), m_edgeMap, and mp_mask.

Referenced by computeCircleCandidates().

◆ computeGradients()

void vpCircleHoughTransform::computeGradients ( const vpImage< unsigned char > & I )

protectedvirtual

Perform Gaussian smoothing on the input image to reduce the noise that would perturbate the edge detection. Then, compute the x-gradient and y-gradient of the input images.

Parameters

[in] I The input gray scale image.

Definition at line 441 of file vpCircleHoughTransform.cpp.

References vpImageFilter::CANNY_GBLUR_SCHARR_FILTERING, vpImageFilter::CANNY_GBLUR_SOBEL_FILTERING, vpArray2D< Type >::data, vpImageFilter::filter(), vpImageFilter::filterX(), vpImageFilter::filterY(), m_algoParams, m_dIx, m_dIy, m_fg, m_gradientFilterX, m_gradientFilterY, mp_mask, vpException::notImplementedError, and vpImageFilter::vpCannyFilteringAndGradientTypeToString().

Referenced by detect().

◆ computeVotingMask()

void vpCircleHoughTransform::computeVotingMask	(	const vpImage< unsigned char > &	I,
		const std::vector< vpImageCircle > &	detections,
		std::optional< vpImage< bool > > &	mask,
		std::optional< std::vector< std::vector< std::pair< unsigned int, unsigned int >>>> &	opt_votingPoints
	)		const

Compute the mask containing pixels that voted for the detections.

Parameters

[in]	I	The image for which we want to have the information.
[in]	detections	Vector containing the list of vpImageCircle for which we want to know the voting points.
[out]	mask	Optional mask where pixels to exclude have a value set to false.
[out]	opt_votingPoints	Optional vector of pairs of pixel coordinates that voted for the detections.

Examples: tutorial-circle-hough.cpp.

Definition at line 372 of file vpCircleHoughTransform.cpp.

References vpImage< Type >::getHeight(), and vpImage< Type >::getWidth().

◆ detect() [1/3]

std::vector< vpImageCircle > vpCircleHoughTransform::detect ( const vpImage< unsigned char > & I )

virtual

Perform Circle Hough Transform to detect the circles in a gray-scale image.

Parameters

[in] I The input gray scale image.

Returns: std::vector<vpImageCircle> The list of 2D circles detected in the image.

Definition at line 295 of file vpCircleHoughTransform.cpp.

References computeCenterCandidates(), computeCircleCandidates(), computeGradients(), edgeDetection(), m_algoParams, m_centerCandidatesList, m_centerVotes, m_circleCandidates, m_circleCandidatesProbabilities, m_circleCandidatesVotes, m_edgePointsList, m_finalCircles, m_finalCircleVotes, and mergeCircleCandidates().

◆ detect() [2/3]

std::vector< vpImageCircle > vpCircleHoughTransform::detect	(	const vpImage< unsigned char > &	I,
		const int &	nbCircles
	)

virtual

Perform Circle Hough Transform to detect the circles in in a gray-scale image. Get only the nbCircles circles having the greatest number of votes.

Parameters

[in]	I	The input gray scale image.
[in]	nbCircles	The number of circles we want to get. If negative, all the circles will be returned, sorted such as result[0] has the highest number of votes and result[end -1] the lowest.

Returns: std::vector<vpImageCircle> The list of 2D circles with the most number of votes detected in the image.

Definition at line 242 of file vpCircleHoughTransform.cpp.

References detect(), m_algoParams, m_finalCircles, m_finalCirclesProbabilities, m_finalCirclesVotingPoints, and m_finalCircleVotes.

◆ detect() [3/3]

std::vector< vpImageCircle > vpCircleHoughTransform::detect ( const vpImage< vpRGBa > & I )

virtual

Convert the input image in a gray-scale image and then perform Circle Hough Transform to detect the circles in it.

Parameters

[in] I The input color image.

Returns: std::vector<vpImageCircle> The list of 2D circles detected in the image.

Examples: tutorial-circle-hough.cpp.

Definition at line 224 of file vpCircleHoughTransform.cpp.

References vpImageConvert::convert().

Referenced by detect().

◆ edgeDetection()

void vpCircleHoughTransform::edgeDetection ( const vpImage< unsigned char > & I )

protectedvirtual

Perform edge detection based on the computed gradients. Stores the edge points and the edge points connectivity.

Parameters

[in] I The input gray scale image.

Definition at line 463 of file vpCircleHoughTransform.cpp.

References vpImageFilter::canny(), vpImageFilter::CANNY_VISP_BACKEND, vpCannyEdgeDetection::detect(), filterEdgeMap(), vpImage< Type >::getHeight(), vpImage< Type >::getWidth(), m_algoParams, m_cannyVisp, m_dIx, m_dIy, m_edgeMap, mp_mask, vpCannyEdgeDetection::setCannyThresholds(), vpCannyEdgeDetection::setCannyThresholdsRatio(), vpCannyEdgeDetection::setFilteringAndGradientType(), vpCannyEdgeDetection::setGradients(), and vpCannyEdgeDetection::setMask().

Referenced by detect().

◆ filterEdgeMap()

void vpCircleHoughTransform::filterEdgeMap ( )

protectedvirtual

Filter the edge map in order to remove isolated edge points.

Definition at line 510 of file vpCircleHoughTransform.cpp.

References edgeMapOff, edgeMapOn, vpImage< Type >::getHeight(), vpImage< Type >::getWidth(), and m_edgeMap.

Referenced by edgeDetection().

◆ getCannyThreshold()

float vpCircleHoughTransform::getCannyThreshold ( ) const

inline

Get internal Canny filter upper threshold. When value is equal to -1 (default), it means that the threshold is computed automatically.

Definition at line 1109 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ getCenterCandidatesList()

std::vector<std::pair<float, float> > vpCircleHoughTransform::getCenterCandidatesList ( ) const

inline

Get the list of Center Candidates, stored as pair <idRow, idCol>

Returns: std::vector<std::pair<float, float> > The list of Center Candidates, stored as pair <idRow, idCol>

Definition at line 1029 of file vpCircleHoughTransform.h.

References m_centerCandidatesList.

◆ getCenterCandidatesVotes()

std::vector<int> vpCircleHoughTransform::getCenterCandidatesVotes ( ) const

inline

Get the number of votes of each Center Candidates.

Returns: std::vector<int> The number of votes of each Center Candidates, ordered in the same way than m_centerCandidatesList.

Definition at line 1039 of file vpCircleHoughTransform.h.

References m_centerVotes.

◆ getCircleCandidates()

std::vector<vpImageCircle> vpCircleHoughTransform::getCircleCandidates ( ) const

inline

Get the Circle Candidates before merging step.

Returns: std::vector<vpImageCircle> The list of circle candidates that were obtained before the merging step.

Definition at line 1050 of file vpCircleHoughTransform.h.

References m_circleCandidates.

◆ getCircleCandidatesProbabilities()

std::vector<float> vpCircleHoughTransform::getCircleCandidatesProbabilities ( ) const

inline

Get the probabilities of the Circle Candidates.

Returns: std::vector<float> The votes accumulator.

Definition at line 1060 of file vpCircleHoughTransform.h.

References m_circleCandidatesProbabilities.

◆ getCircleCandidatesVotes()

std::vector<unsigned int> vpCircleHoughTransform::getCircleCandidatesVotes ( ) const

inline

Get the votes of the circle candidates.

Returns: std::vector<unsigned int> The votes of the circle candidates.

Definition at line 1070 of file vpCircleHoughTransform.h.

References m_circleCandidatesVotes.

◆ getCircleCenterMinDist()

float vpCircleHoughTransform::getCircleCenterMinDist ( ) const

inline

Get circles center min distance in pixels.

Definition at line 1117 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ getCircleMaxRadius()

float vpCircleHoughTransform::getCircleMaxRadius ( ) const

inline

Get circles max radius in pixels.

Definition at line 1133 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ getCircleMinRadius()

float vpCircleHoughTransform::getCircleMinRadius ( ) const

inline

Get circles min radius in pixels.

Definition at line 1125 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ getDetectionsProbabilities()

std::vector<float> vpCircleHoughTransform::getDetectionsProbabilities ( ) const

inline

Get the probabilities of the detections that are outputed by vpCircleHoughTransform::detect()

Examples: tutorial-circle-hough.cpp.

Definition at line 1141 of file vpCircleHoughTransform.h.

References m_finalCirclesProbabilities.

◆ getDetectionsVotes()

std::vector<unsigned int> vpCircleHoughTransform::getDetectionsVotes ( ) const

inline

Get the number of votes for the detections that are outputed by vpCircleHoughTransform::detect()

Definition at line 1149 of file vpCircleHoughTransform.h.

References m_finalCircleVotes.

◆ getEdgeMap()

vpImage<unsigned char> vpCircleHoughTransform::getEdgeMap ( ) const

inline

Get the Edge Map computed thanks to the Canny edge filter.

Returns: vpImage<unsigned char> The edge map computed during the edge detection step.

Examples: tutorial-circle-hough.cpp.

Definition at line 1100 of file vpCircleHoughTransform.h.

References m_edgeMap.

◆ getGradientX()

vpImage<float> vpCircleHoughTransform::getGradientX ( ) const

inline

Get the gradient along the horizontal axis of the image.

Returns: vpImage<float> The gradient along the horizontal axis of the image.

Definition at line 1080 of file vpCircleHoughTransform.h.

References m_dIx.

◆ getGradientY()

vpImage<float> vpCircleHoughTransform::getGradientY ( ) const

inline

Get the gradient along the vertical axis of the image.

Returns: vpImage<float> The gradient along the vertical axis of the image.

Definition at line 1090 of file vpCircleHoughTransform.h.

References m_dIy.

◆ init()

void vpCircleHoughTransform::init ( const vpCircleHoughTransformParameters & algoParams )

Initialize all the algorithm parameters.

Parameters

[in] algoParams The algorithm parameters.

Examples: tutorial-circle-hough.cpp.

Definition at line 115 of file vpCircleHoughTransform.cpp.

References initGaussianFilters(), initGradientFilters(), and m_algoParams.

◆ initFromJSON()

void vpCircleHoughTransform::initFromJSON ( const std::string & jsonPath )

virtual

Initialize all the algorithm parameters using the JSON file whose path is jsonPath. Throw a vpException error if the file does not exist.

Parameters

[in] jsonPath The path towards the JSON configuration file.

Examples: tutorial-circle-hough.cpp.

Definition at line 134 of file vpCircleHoughTransform.cpp.

References initGaussianFilters(), initGradientFilters(), vpException::ioError, and m_algoParams.

Referenced by vpCircleHoughTransform().

◆ initGaussianFilters()

void vpCircleHoughTransform::initGaussianFilters ( )

protectedvirtual

Initialize the Gaussian filters used to blur the image and compute the gradient images.

Definition at line 168 of file vpCircleHoughTransform.cpp.

References vpArray2D< Type >::data, vpImageFilter::getGaussianKernel(), m_algoParams, m_cannyVisp, m_fg, vpArray2D< Type >::resize(), and vpCannyEdgeDetection::setGaussianFilterParameters().

Referenced by init(), initFromJSON(), setGaussianParameters(), and vpCircleHoughTransform().

◆ initGradientFilters()

void vpCircleHoughTransform::initGradientFilters ( )

protectedvirtual

Initialize the gradient filters used to compute the gradient images.

Definition at line 177 of file vpCircleHoughTransform.cpp.

References vpException::badValue, vpImageFilter::CANNY_GBLUR_SCHARR_FILTERING, vpImageFilter::CANNY_GBLUR_SOBEL_FILTERING, vpArray2D< Type >::data, vpArray2D< Type >::getCols(), vpArray2D< Type >::getRows(), vpImageFilter::getScharrKernelX(), vpImageFilter::getScharrKernelY(), vpImageFilter::getSobelKernelX(), vpImageFilter::getSobelKernelY(), m_algoParams, m_cannyVisp, m_gradientFilterX, m_gradientFilterY, vpException::notImplementedError, vpArray2D< Type >::resize(), vpCannyEdgeDetection::setGradientFilterAperture(), and vpImageFilter::vpCannyFilteringAndGradientTypeToString().

Referenced by init(), initFromJSON(), setFilteringAndGradientType(), setGradientFilterAperture(), and vpCircleHoughTransform().

◆ mergeCandidates()

void vpCircleHoughTransform::mergeCandidates	(	std::vector< vpImageCircle > &	circleCandidates,
		std::vector< unsigned int > &	circleCandidatesVotes,
		std::vector< float > &	circleCandidatesProba,
		std::vector< std::vector< std::pair< unsigned int, unsigned int > > > &	votingPoints
	)

protectedvirtual

For each circle candidate CiC_i do:

For each other circle candidate CiC_j do: +- Compute the similarity between CiC_i and CiC_j +- If the similarity exceeds a threshold, merge the circle candidates CiC_i and CiC_j and remove CiC_j of the list

Add the circle candidate CiC_i to the final list of detected circles

Parameters

[out]	circleCandidates	List of circle candidates in which we want to merge the similar circles.
[out]	circleCandidatesVotes	List of votes of the circle candidates.
[out]	circleCandidatesProba	List of probabilities of the circle candidates.
[out]	votingPoints	List of edge-map points having voted of the circle candidates.

Definition at line 1123 of file vpCircleHoughTransform.cpp.

References vpImagePoint::distance(), vpImageCircle::getCenter(), vpImageCircle::getRadius(), and m_algoParams.

Referenced by mergeCircleCandidates().

◆ mergeCircleCandidates()

void vpCircleHoughTransform::mergeCircleCandidates ( )

protectedvirtual

For each circle candidate CiC_i, check if similar circles have also been detected and if so merges them.

Definition at line 1103 of file vpCircleHoughTransform.cpp.

References m_circleCandidates, m_circleCandidatesProbabilities, m_circleCandidatesVotes, m_circleCandidatesVotingPoints, m_finalCircles, m_finalCirclesProbabilities, m_finalCirclesVotingPoints, m_finalCircleVotes, and mergeCandidates().

Referenced by detect().

◆ saveConfigurationInJSON()

void vpCircleHoughTransform::saveConfigurationInJSON ( const std::string & jsonPath ) const

virtual

Save the configuration of the detector in a JSON file described by the path jsonPath. Throw a vpException is the file cannot be created.

Parameters

[in] jsonPath The path towards the JSON output file.

Definition at line 161 of file vpCircleHoughTransform.cpp.

References m_algoParams, and vpCircleHoughTransform::vpCircleHoughTransformParameters::saveConfigurationInJSON().

◆ setCannyBackend()

void vpCircleHoughTransform::setCannyBackend ( const vpImageFilter::vpCannyBackendType & type )

inline

Set the backend to use to perform the Canny edge detection.

Parameters

[in] type The backend that must be used.

Definition at line 848 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ setCannyThreshold()

void vpCircleHoughTransform::setCannyThreshold	(	const float &	lowerCannyThreshold,
		const float &	upperCannyThreshold
	)

inline

Set the threshold for the Canny operator. Only value greater than this value are marked as an edge. If negative, the threshold is automatically computed.

Parameters

[in]	lowerCannyThreshold	: Canny filter lower threshold. When set to -1 (default), compute automatically this threshold.
[in]	upperCannyThreshold	: Canny filter upper threshold. When set to -1 (default), compute automatically this threshold.

Definition at line 862 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ setCannyThresholdRatio()

void vpCircleHoughTransform::setCannyThresholdRatio	(	const float &	lowerThreshRatio,
		const float &	upperThreshRatio
	)

inline

Set the Canny thresholds ratio that are used to automatically compute the Canny thresholds in case the user asks to.

See also: vpCircleHoughTransform::setCannyThreshold(const float&, const float&)

Parameters

[in]	lowerThreshRatio	The ratio of the upper threshold the lower threshold will be equal to.
[in]	upperThreshRatio	The ratio of pixels that must have a gradient lower than the upper threshold.

Definition at line 877 of file vpCircleHoughTransform.h.

References m_algoParams, m_cannyVisp, and vpCannyEdgeDetection::setCannyThresholdsRatio().

◆ setCenterComputationParameters()

void vpCircleHoughTransform::setCenterComputationParameters	(	const int &	dilatationSize,
		const float &	centerThresh,
		const int &	averagingWindowSize = `5`,
		const int	expectedNbCenters = `-1`
	)

inline

Set the parameters of the computation of the circle center candidates.

Parameters

[in]	dilatationSize	Kernel size of the dilatation operation used to detect the maxima in the center accumulator.
[in]	centerThresh	Minimum number of votes a point must exceed to be considered as center candidate.
[in]	averagingWindowSize	Size of the averaging window around the maximum number of votes to compute the center candidate such as it is the barycenter of the window. Must be odd.
[in]	expectedNbCenters	Expected number of centers in the image. If the number is negative, all the centers are kept. Otherwise, maximum up to this number of centers are kept.

Definition at line 963 of file vpCircleHoughTransform.h.

References vpException::badValue, and m_algoParams.

◆ setCircleCenterBoundingBox()

void vpCircleHoughTransform::setCircleCenterBoundingBox	(	const int &	center_min_x,
		const int &	center_max_x,
		const int &	center_min_y,
		const int &	center_max_y
	)

inline

Set circles center min and max location in the image. If one value is equal to std::numeric_limits<int>::min or std::numeric_limits<int>::max(), the algorithm will set it either to -maxRadius or +maxRadius depending on if it is the lower or upper limit that is missing.

Parameters

[in]	center_min_x	: Center min location on the horizontal axis, expressed in pixels.
[in]	center_max_x	: Center max location on the horizontal axis, expressed in pixels.
[in]	center_min_y	: Center min location on the vertical axis, expressed in pixels.
[in]	center_max_y	: Center max location on the vertical axis, expressed in pixels.

Definition at line 911 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ setCircleCenterMinDist()

void vpCircleHoughTransform::setCircleCenterMinDist ( const float & center_min_dist )

inline

Set circles center min distance. Change this value to detect circles with different distances to each other.

Parameters

[in] center_min_dist : Center min distance in pixels.

Definition at line 890 of file vpCircleHoughTransform.h.

References vpException::badValue, and m_algoParams.

◆ setCircleMaxRadius()

void vpCircleHoughTransform::setCircleMaxRadius ( const float & circle_max_radius )

inline

Set circles max radius.

Parameters

[in] circle_max_radius : Max radius in pixels.

Definition at line 933 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ setCircleMinRadius()

void vpCircleHoughTransform::setCircleMinRadius ( const float & circle_min_radius )

inline

Set circles min radius.

Parameters

[in] circle_min_radius : Min radius in pixels.

Definition at line 924 of file vpCircleHoughTransform.h.

References m_algoParams.

◆ setCirclePerfectness()

void vpCircleHoughTransform::setCirclePerfectness ( const float & circle_perfectness )

inline

Set circles perfectness, which corresponds to the threshold of the colinearity between the gradient of a point and the radius it would form with a center candidate to be able to vote. The formula to get the equivalent angle is: angle = acos(circle_perfectness).

Parameters

[in] circle_perfectness : Circle perfectness. Value between 0 and 1. A perfect circle has value 1.

Definition at line 945 of file vpCircleHoughTransform.h.

References vpException::badValue, and m_algoParams.

◆ setFilteringAndGradientType()

void vpCircleHoughTransform::setFilteringAndGradientType ( const vpImageFilter::vpCannyFilteringAndGradientType & type )

inline

Permits to choose the filtering + gradient operators to use.

Parameters

[in] type The type of filtering + gradient operators to use.

Definition at line 797 of file vpCircleHoughTransform.h.

References initGradientFilters(), m_algoParams, m_cannyVisp, and vpCannyEdgeDetection::setFilteringAndGradientType().

◆ setGaussianParameters()

void vpCircleHoughTransform::setGaussianParameters	(	const int &	kernelSize,
		const float &	stdev
	)

inline

Set the parameters of the Gaussian filter, that permits to blur the gradients of the image.

Parameters

[in]	kernelSize	The size of the Gaussian kernel. Must be an odd value.
[in]	stdev	The standard deviation of the Gaussian function.

Definition at line 811 of file vpCircleHoughTransform.h.

References vpException::badValue, initGaussianFilters(), and m_algoParams.

◆ setGradientFilterAperture()

void vpCircleHoughTransform::setGradientFilterAperture ( const unsigned int & apertureSize )

inline

Set the parameters of the gradient filter (Sobel or Scharr) kernel size filters.

Parameters

[in] apertureSize The size of the gradient filters kernel. Must be an odd value.

Definition at line 832 of file vpCircleHoughTransform.h.

References vpException::badValue, initGradientFilters(), and m_algoParams.

◆ setMask()

void vpCircleHoughTransform::setMask ( const vpImage< bool > & mask )

inline

Definition at line 1016 of file vpCircleHoughTransform.h.

References mp_mask.

◆ setRadiusMergingThresholds()

void vpCircleHoughTransform::setRadiusMergingThresholds ( const float & radiusDifferenceThresh )

inline

Set the radius merging threshold used during the merging step in order to merge the circles that are similar.

Parameters

[in] radiusDifferenceThresh Maximum radius difference between two circle candidates to consider merging them.

Definition at line 1007 of file vpCircleHoughTransform.h.

References vpException::badValue, and m_algoParams.

◆ setRadiusRatioThreshold()

void vpCircleHoughTransform::setRadiusRatioThreshold ( const float & radiusRatioThresh )

inline

Set the parameters of the computation of the circle radius candidates.

Parameters

[in] radiusRatioThresh Minimum number of votes per radian a radius candidate RC_ij of a center candidate CeC_i must have in order that the circle of center CeC_i and radius RC_ij must be considered as circle candidate.

Definition at line 992 of file vpCircleHoughTransform.h.

References vpException::badValue, and m_algoParams.

◆ toString()

std::string vpCircleHoughTransform::toString ( ) const

Create a string with all Hough transform parameters.

Definition at line 1195 of file vpCircleHoughTransform.cpp.

References m_algoParams, and vpCircleHoughTransform::vpCircleHoughTransformParameters::toString().

Friends And Related Function Documentation

◆ from_json

void from_json	(	const nlohmann::json &	j,
		vpCircleHoughTransform &	detector
	)

friend

Read the detector configuration from JSON. All values are optional and if an argument is not present, the default value defined in the constructor is kept.

Parameters

[in]	j	The JSON object, resulting from the parsing of a JSON file.
[out]	detector	The detector, that will be initialized from the JSON data.

Definition at line 765 of file vpCircleHoughTransform.h.

◆ operator<<

VISP_EXPORT std::ostream& operator<<	(	std::ostream &	os,
		const vpCircleHoughTransform &	detector
	)

friend

Create a ostream with all Hough transform parameters.

Definition at line 1200 of file vpCircleHoughTransform.cpp.

◆ to_json

void to_json	(	nlohmann::json &	j,
		const vpCircleHoughTransform &	detector
	)

friend

Parse a vpCircleHoughTransform into JSON format.

Parameters

[out]	j	A JSON parser object.
[in]	detector	The vpCircleHoughTransform that must be parsed into JSON format.

Definition at line 776 of file vpCircleHoughTransform.h.

Member Data Documentation

◆ edgeMapOff

const unsigned char vpCircleHoughTransform::edgeMapOff = 0

static

Definition at line 1166 of file vpCircleHoughTransform.h.

Referenced by filterEdgeMap().

◆ edgeMapOn

const unsigned char vpCircleHoughTransform::edgeMapOn = 255

static

Definition at line 1165 of file vpCircleHoughTransform.h.

Referenced by computeCenterCandidates(), and filterEdgeMap().

◆ m_algoParams

vpCircleHoughTransformParameters vpCircleHoughTransform::m_algoParams

protected

◆ m_cannyVisp

vpCannyEdgeDetection vpCircleHoughTransform::m_cannyVisp

protected

Edge detector ViSP implementation, used if ViSP has not been compiled with OpenCV imgproc module

Definition at line 1262 of file vpCircleHoughTransform.h.

Referenced by edgeDetection(), initGaussianFilters(), initGradientFilters(), setCannyThresholdRatio(), and setFilteringAndGradientType().

◆ m_centerCandidatesList

std::vector<std::pair<float, float> > vpCircleHoughTransform::m_centerCandidatesList

protected

Vector that contains the list of center candidates. They are stored as pair <row, col>.

Definition at line 1267 of file vpCircleHoughTransform.h.

Referenced by computeCenterCandidates(), computeCircleCandidates(), detect(), and getCenterCandidatesList().

◆ m_centerVotes

std::vector<int> vpCircleHoughTransform::m_centerVotes

protected

Number of votes for the center candidates that are kept.

Definition at line 1268 of file vpCircleHoughTransform.h.

Referenced by computeCenterCandidates(), detect(), and getCenterCandidatesVotes().

◆ m_circleCandidates

std::vector<vpImageCircle> vpCircleHoughTransform::m_circleCandidates

protected

List of the candidate circles.

Definition at line 1271 of file vpCircleHoughTransform.h.

Referenced by computeCircleCandidates(), detect(), getCircleCandidates(), and mergeCircleCandidates().

◆ m_circleCandidatesProbabilities

std::vector<float> vpCircleHoughTransform::m_circleCandidatesProbabilities

protected

Probabilities of each candidate circle that is kept.

Definition at line 1272 of file vpCircleHoughTransform.h.

Referenced by computeCircleCandidates(), detect(), getCircleCandidatesProbabilities(), and mergeCircleCandidates().

◆ m_circleCandidatesVotes

std::vector<unsigned int> vpCircleHoughTransform::m_circleCandidatesVotes

protected

Number of pixels voting for each candidate circle that is kept.

Definition at line 1273 of file vpCircleHoughTransform.h.

Referenced by computeCircleCandidates(), detect(), getCircleCandidatesVotes(), and mergeCircleCandidates().

◆ m_circleCandidatesVotingPoints

std::vector<std::vector<std::pair<unsigned int, unsigned int> > > vpCircleHoughTransform::m_circleCandidatesVotingPoints

protected

Points that voted for each circle candidate.

Definition at line 1274 of file vpCircleHoughTransform.h.

Referenced by computeCircleCandidates(), and mergeCircleCandidates().

◆ m_dIx

vpImage<float> vpCircleHoughTransform::m_dIx

protected

Gradient along the x-axis of the input image.

Definition at line 1258 of file vpCircleHoughTransform.h.

Referenced by computeCenterCandidates(), computeCircleCandidates(), computeGradients(), edgeDetection(), and getGradientX().

◆ m_dIy

vpImage<float> vpCircleHoughTransform::m_dIy

protected

Gradient along the y-axis of the input image.

Definition at line 1259 of file vpCircleHoughTransform.h.

Referenced by computeCenterCandidates(), computeCircleCandidates(), computeGradients(), edgeDetection(), and getGradientY().

◆ m_edgeMap

vpImage<unsigned char> vpCircleHoughTransform::m_edgeMap

protected

Edge map resulting from the edge detection algorithm.

Definition at line 1263 of file vpCircleHoughTransform.h.

Referenced by computeCenterCandidates(), computeCircleProbability(), edgeDetection(), filterEdgeMap(), and getEdgeMap().

◆ m_edgePointsList

std::vector<std::pair<unsigned int, unsigned int> > vpCircleHoughTransform::m_edgePointsList

protected

Vector that contains the list of edge points, to make faster some parts of the algo. They are stored as pair <row, col>.

Definition at line 1266 of file vpCircleHoughTransform.h.

Referenced by computeCenterCandidates(), computeCircleCandidates(), and detect().

◆ m_fg

vpArray2D<float> vpCircleHoughTransform::m_fg

protected

Definition at line 1252 of file vpCircleHoughTransform.h.

Referenced by computeGradients(), and initGaussianFilters().

◆ m_finalCircles

std::vector<vpImageCircle> vpCircleHoughTransform::m_finalCircles

protected

List of the final circles, i.e. the ones resulting from the merge of the circle candidates.

Definition at line 1277 of file vpCircleHoughTransform.h.

Referenced by detect(), and mergeCircleCandidates().

◆ m_finalCirclesProbabilities

std::vector<float> vpCircleHoughTransform::m_finalCirclesProbabilities

protected

Probabilities of each final circle, i.e. resulting from the merge of the circle candidates.

Definition at line 1278 of file vpCircleHoughTransform.h.

Referenced by detect(), getDetectionsProbabilities(), and mergeCircleCandidates().

◆ m_finalCirclesVotingPoints

std::vector<std::vector<std::pair<unsigned int, unsigned int> > > vpCircleHoughTransform::m_finalCirclesVotingPoints

protected

Points that voted for each final circle.

Definition at line 1280 of file vpCircleHoughTransform.h.

Referenced by detect(), and mergeCircleCandidates().

◆ m_finalCircleVotes

std::vector<unsigned int> vpCircleHoughTransform::m_finalCircleVotes

protected

Number of votes for the final circles.

Definition at line 1279 of file vpCircleHoughTransform.h.

Referenced by detect(), getDetectionsVotes(), and mergeCircleCandidates().

◆ m_gradientFilterX

vpArray2D<float> vpCircleHoughTransform::m_gradientFilterX

protected

Contains the coefficients of the gradient kernel along the X-axis

Definition at line 1256 of file vpCircleHoughTransform.h.

Referenced by computeGradients(), and initGradientFilters().

◆ m_gradientFilterY

vpArray2D<float> vpCircleHoughTransform::m_gradientFilterY

protected

Contains the coefficients of the gradient kernel along the Y-axis

Definition at line 1257 of file vpCircleHoughTransform.h.

Referenced by computeGradients(), and initGradientFilters().

◆ mp_mask

const vpImage<bool>* vpCircleHoughTransform::mp_mask

protected

Mask that permits to avoid to compute gradients on some regions of the image.

Definition at line 1255 of file vpCircleHoughTransform.h.

Referenced by computeCircleProbability(), computeGradients(), edgeDetection(), and setMask().

Classes

Public Member Functions

Getters

Configuration from files

Detailed Description

Constructor & Destructor Documentation

◆ vpCircleHoughTransform() [1/3]

◆ vpCircleHoughTransform() [2/3]

◆ ~vpCircleHoughTransform()

◆ vpCircleHoughTransform() [3/3]

Member Function Documentation

◆ computeCenterCandidates()

◆ computeCircleCandidates()

◆ computeCircleProbability()

◆ computeGradients()

◆ computeVotingMask()

◆ detect() [1/3]

◆ detect() [2/3]

◆ detect() [3/3]

◆ edgeDetection()

◆ filterEdgeMap()

◆ getCannyThreshold()

◆ getCenterCandidatesList()

◆ getCenterCandidatesVotes()

◆ getCircleCandidates()

◆ getCircleCandidatesProbabilities()

◆ getCircleCandidatesVotes()

◆ getCircleCenterMinDist()

◆ getCircleMaxRadius()

◆ getCircleMinRadius()

◆ getDetectionsProbabilities()

◆ getDetectionsVotes()

◆ getEdgeMap()

◆ getGradientX()

◆ getGradientY()

◆ init()

◆ initFromJSON()

◆ initGaussianFilters()

◆ initGradientFilters()

◆ mergeCandidates()

◆ mergeCircleCandidates()

◆ saveConfigurationInJSON()

◆ setCannyBackend()

◆ setCannyThreshold()

◆ setCannyThresholdRatio()

◆ setCenterComputationParameters()

◆ setCircleCenterBoundingBox()

◆ setCircleCenterMinDist()

◆ setCircleMaxRadius()

◆ setCircleMinRadius()

◆ setCirclePerfectness()

◆ setFilteringAndGradientType()

◆ setGaussianParameters()

◆ setGradientFilterAperture()

◆ setMask()

◆ setRadiusMergingThresholds()

◆ setRadiusRatioThreshold()

◆ toString()

Friends And Related Function Documentation

◆ from_json

◆ operator<<

◆ to_json

Member Data Documentation

◆ edgeMapOff

◆ edgeMapOn

◆ m_algoParams

◆ m_cannyVisp

◆ m_centerCandidatesList

◆ m_centerVotes

◆ m_circleCandidates

◆ m_circleCandidatesProbabilities

◆ m_circleCandidatesVotes

◆ m_circleCandidatesVotingPoints

◆ m_dIx

◆ m_dIy

◆ m_edgeMap

◆ m_edgePointsList

◆ m_fg

◆ m_finalCircles

◆ m_finalCirclesProbabilities