Visual Servoing Platform  version 3.6.1 under development (2024-07-18)

#include <visp3/imgproc/vpCircleHoughTransform.h>

Classes

class  vpCircleHoughTransformParams
 

Public Types

typedef vpCircleHoughTransformParams vpCircleHoughTransformParameters
 

Public Member Functions

 vpCircleHoughTransform ()
 
VP_EXPLICIT vpCircleHoughTransform (const vpCircleHoughTransformParams &algoParams)
 
virtual ~vpCircleHoughTransform ()
 
Detection methods
virtual std::vector< vpImageCircledetect (const vpImage< vpRGBa > &I)
 
virtual std::vector< vpImageCircledetect (const vpImage< unsigned char > &I)
 
virtual std::vector< vpImageCircledetect (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 vpCircleHoughTransformParams &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
 
vpCircleHoughTransformParams 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< vpImageCirclem_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< vpImageCirclem_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< vpImageCirclegetCircleCandidates () 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 void filterCenterCandidates (const std::vector< vpCenterVotes > &peak_positions_votes)
 
virtual vpCentersBarycenter mergeSimilarCenters (const unsigned int &idPeak, const unsigned int &nbPeaks, const float &squared_distance_max, const std::vector< vpCenterVotes > &peak_positions_votes, std::vector< bool > &has_been_merged)
 
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

VP_EXPLICIT 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 64 of file vpCircleHoughTransform.h.

Member Typedef Documentation

◆ vpCircleHoughTransformParameters

Constructor & Destructor Documentation

◆ vpCircleHoughTransform() [1/3]

BEGIN_VISP_NAMESPACE vpCircleHoughTransform::vpCircleHoughTransform ( )

Construct a new vpCircleHoughTransform object with default parameters.

Definition at line 63 of file vpCircleHoughTransform_common.cpp.

References initGaussianFilters(), and initGradientFilters().

◆ vpCircleHoughTransform() [2/3]

vpCircleHoughTransform::vpCircleHoughTransform ( const vpCircleHoughTransformParams algoParams)

Construct a new vpCircleHoughTransform object from a vpCircleHoughTransformParams object.

Parameters
[in]algoParamsThe parameters of the Circle Hough Transform.

Definition at line 71 of file vpCircleHoughTransform_common.cpp.

References initGaussianFilters(), and initGradientFilters().

◆ ~vpCircleHoughTransform()

vpCircleHoughTransform::~vpCircleHoughTransform ( )
virtual

Destroy the vp Circle Hough Transform object.

Definition at line 87 of file vpCircleHoughTransform_common.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]jsonPathThe path towards the JSON configuration file.

Definition at line 93 of file vpCircleHoughTransform_common.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 340 of file vpCircleHoughTransform_centers.cpp.

References BEGIN_VISP_NAMESPACE::vpDataForAccumLoop::accumulatorHeight, vpException::badValue, vpImageMorphology::dilatation(), vpException::dimensionError, edgeMapOn, vpMath::equal(), filterCenterCandidates(), vpImage< Type >::getCols(), vpImage< Type >::getRows(), m_algoParams, 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 133 of file vpCircleHoughTransform_circles.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
[in]circleThe circle for which we want to evaluate the probability.
[in]nbVotesThe number of visible pixels of the given circle.
Returns
float The probability of the circle.

Definition at line 274 of file vpCircleHoughTransform_circles.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]IThe input gray scale image.

Definition at line 234 of file vpCircleHoughTransform_centers.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::vpCannyFiltAndGradTypeToStr().

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]IThe image for which we want to have the information.
[in]detectionsVector containing the list of vpImageCircle for which we want to know the voting points.
[out]maskOptional mask where pixels to exclude have a value set to false.
[out]opt_votingPointsOptional vector of pairs of pixel coordinates that voted for the detections.
Examples
tutorial-circle-hough.cpp.

Definition at line 338 of file vpCircleHoughTransform_common.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]IThe input gray scale image.
Returns
std::vector<vpImageCircle> The list of 2D circles detected in the image.

Definition at line 261 of file vpCircleHoughTransform_common.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]IThe input gray scale image.
[in]nbCirclesThe 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 208 of file vpCircleHoughTransform_common.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]IThe input color image.
Returns
std::vector<vpImageCircle> The list of 2D circles detected in the image.
Examples
tutorial-circle-hough.cpp.

Definition at line 190 of file vpCircleHoughTransform_common.cpp.

References vpImageConvert::convert().

Referenced by detect().

◆ edgeDetection()

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

◆ filterCenterCandidates()

void vpCircleHoughTransform::filterCenterCandidates ( const std::vector< vpCenterVotes > &  peak_positions_votes)
protectedvirtual

Aggregate center candidates that are close to each other.

Parameters
[in]peak_positions_votesVector containing raw center candidates.

Definition at line 480 of file vpCircleHoughTransform_centers.cpp.

References m_algoParams, m_centerCandidatesList, m_centerVotes, and mergeSimilarCenters().

Referenced by computeCenterCandidates().

◆ filterEdgeMap()

void vpCircleHoughTransform::filterEdgeMap ( )
protectedvirtual

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

Definition at line 303 of file vpCircleHoughTransform_centers.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 1138 of file vpCircleHoughTransform.h.

◆ 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 1058 of file vpCircleHoughTransform.h.

◆ 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 1068 of file vpCircleHoughTransform.h.

◆ 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 1079 of file vpCircleHoughTransform.h.

◆ 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 1089 of file vpCircleHoughTransform.h.

◆ 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 1099 of file vpCircleHoughTransform.h.

◆ getCircleCenterMinDist()

float vpCircleHoughTransform::getCircleCenterMinDist ( ) const
inline

Get circles center min distance in pixels.

Definition at line 1146 of file vpCircleHoughTransform.h.

◆ getCircleMaxRadius()

float vpCircleHoughTransform::getCircleMaxRadius ( ) const
inline

Get circles max radius in pixels.

Definition at line 1162 of file vpCircleHoughTransform.h.

◆ getCircleMinRadius()

float vpCircleHoughTransform::getCircleMinRadius ( ) const
inline

Get circles min radius in pixels.

Definition at line 1154 of file vpCircleHoughTransform.h.

◆ 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 1170 of file vpCircleHoughTransform.h.

◆ 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 1178 of file vpCircleHoughTransform.h.

◆ 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 1129 of file vpCircleHoughTransform.h.

◆ 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 1109 of file vpCircleHoughTransform.h.

◆ 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 1119 of file vpCircleHoughTransform.h.

◆ init()

void vpCircleHoughTransform::init ( const vpCircleHoughTransformParams algoParams)

Initialize all the algorithm parameters.

Parameters
[in]algoParamsThe algorithm parameters.
Examples
tutorial-circle-hough.cpp.

Definition at line 80 of file vpCircleHoughTransform_common.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]jsonPathThe path towards the JSON configuration file.
Examples
tutorial-circle-hough.cpp.

Definition at line 99 of file vpCircleHoughTransform_common.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 133 of file vpCircleHoughTransform_common.cpp.

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

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

◆ initGradientFilters()

◆ 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]circleCandidatesList of circle candidates in which we want to merge the similar circles.
    [out]circleCandidatesVotesList of votes of the circle candidates.
    [out]circleCandidatesProbaList of probabilities of the circle candidates.
    [out]votingPointsList of edge-map points having voted of the circle candidates.

Definition at line 315 of file vpCircleHoughTransform_circles.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 295 of file vpCircleHoughTransform_circles.cpp.

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

Referenced by detect().

◆ mergeSimilarCenters()

vpCircleHoughTransform::vpCentersBarycenter vpCircleHoughTransform::mergeSimilarCenters ( const unsigned int &  idPeak,
const unsigned int &  nbPeaks,
const float &  squared_distance_max,
const std::vector< vpCenterVotes > &  peak_positions_votes,
std::vector< bool > &  has_been_merged 
)
protectedvirtual

Look in the list containing the raw center candidates if one is closed to the center candidate that is currently of interest.

Parameters
[in]idPeakThe ID of the center candidate that is currently of interest.
[in]nbPeaksThe number of center candidates.
[in]squared_distance_maxThe maximum squared distance between to center candidates to merge them.
[in]peak_positions_votesThe list containing the raw center candidates.
[out]has_been_mergedVector indicating if the center candidates have already been merged.
Returns
vpCentersBarycenter The barycenter between the center candidate that is currently of interest and similar center candidates.

Definition at line 532 of file vpCircleHoughTransform_centers.cpp.

References m_algoParams.

Referenced by filterCenterCandidates().

◆ 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]jsonPathThe path towards the JSON output file.

Definition at line 126 of file vpCircleHoughTransform_common.cpp.

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

◆ setCannyBackend()

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

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

Parameters
[in]typeThe backend that must be used.

Definition at line 875 of file vpCircleHoughTransform.h.

◆ 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 889 of file vpCircleHoughTransform.h.

◆ 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]lowerThreshRatioThe ratio of the upper threshold the lower threshold will be equal to.
[in]upperThreshRatioThe ratio of pixels that must have a gradient lower than the upper threshold.

Definition at line 904 of file vpCircleHoughTransform.h.

◆ 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]dilatationSizeKernel size of the dilatation operation used to detect the maxima in the center accumulator.
[in]centerThreshMinimum number of votes a point must exceed to be considered as center candidate.
[in]averagingWindowSizeSize 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]expectedNbCentersExpected 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 990 of file vpCircleHoughTransform.h.

References vpException::badValue.

◆ 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 938 of file vpCircleHoughTransform.h.

◆ 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 917 of file vpCircleHoughTransform.h.

References vpException::badValue.

◆ 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 960 of file vpCircleHoughTransform.h.

◆ 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 951 of file vpCircleHoughTransform.h.

◆ 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 972 of file vpCircleHoughTransform.h.

References vpException::badValue.

◆ setFilteringAndGradientType()

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

Permits to choose the filtering + gradient operators to use.

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

Definition at line 822 of file vpCircleHoughTransform.h.

◆ 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]kernelSizeThe size of the Gaussian kernel. Must be an odd value.
[in]stdevThe standard deviation of the Gaussian function.

Definition at line 836 of file vpCircleHoughTransform.h.

References vpException::badValue.

◆ setGradientFilterAperture()

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

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

Parameters
[in]apertureSizeThe size of the gradient filters kernel. Must be an odd value.

Definition at line 858 of file vpCircleHoughTransform.h.

References vpException::badValue.

◆ setMask()

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

Definition at line 1045 of file vpCircleHoughTransform.h.

◆ 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]radiusDifferenceThreshMaximum radius difference between two circle candidates to consider merging them.

Definition at line 1036 of file vpCircleHoughTransform.h.

References vpException::badValue.

◆ setRadiusRatioThreshold()

void vpCircleHoughTransform::setRadiusRatioThreshold ( const float &  radiusRatioThresh)
inline

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

Parameters
[in]radiusRatioThreshMinimum 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 1021 of file vpCircleHoughTransform.h.

References vpException::badValue.

◆ toString()

std::string vpCircleHoughTransform::toString ( ) const

Create a string with all Hough transform parameters.

Definition at line 407 of file vpCircleHoughTransform_common.cpp.

References m_algoParams, and vpCircleHoughTransform::vpCircleHoughTransformParams::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]jThe JSON object, resulting from the parsing of a JSON file.
[out]detectorThe detector, that will be initialized from the JSON data.

Definition at line 790 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 412 of file vpCircleHoughTransform_common.cpp.

◆ to_json

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

Parse a vpCircleHoughTransform into JSON format.

Parameters
[out]jA JSON parser object.
[in]detectorThe vpCircleHoughTransform that must be parsed into JSON format.

Definition at line 801 of file vpCircleHoughTransform.h.

Member Data Documentation

◆ edgeMapOff

const unsigned char vpCircleHoughTransform::edgeMapOff = 0
static

Definition at line 1195 of file vpCircleHoughTransform.h.

Referenced by filterEdgeMap().

◆ edgeMapOn

const unsigned char vpCircleHoughTransform::edgeMapOn = 255
static

Definition at line 1194 of file vpCircleHoughTransform.h.

Referenced by computeCenterCandidates(), and filterEdgeMap().

◆ m_algoParams

◆ 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 1323 of file vpCircleHoughTransform.h.

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

◆ 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 1328 of file vpCircleHoughTransform.h.

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

◆ m_centerVotes

std::vector<int> vpCircleHoughTransform::m_centerVotes
protected

Number of votes for the center candidates that are kept.

Definition at line 1329 of file vpCircleHoughTransform.h.

Referenced by detect(), and filterCenterCandidates().

◆ m_circleCandidates

std::vector<vpImageCircle> vpCircleHoughTransform::m_circleCandidates
protected

List of the candidate circles.

Definition at line 1332 of file vpCircleHoughTransform.h.

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

◆ m_circleCandidatesProbabilities

std::vector<float> vpCircleHoughTransform::m_circleCandidatesProbabilities
protected

Probabilities of each candidate circle that is kept.

Definition at line 1333 of file vpCircleHoughTransform.h.

Referenced by computeCircleCandidates(), detect(), 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 1334 of file vpCircleHoughTransform.h.

Referenced by computeCircleCandidates(), detect(), 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 1335 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 1319 of file vpCircleHoughTransform.h.

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

◆ m_dIy

vpImage<float> vpCircleHoughTransform::m_dIy
protected

Gradient along the y-axis of the input image.

Definition at line 1320 of file vpCircleHoughTransform.h.

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

◆ m_edgeMap

vpImage<unsigned char> vpCircleHoughTransform::m_edgeMap
protected

Edge map resulting from the edge detection algorithm.

Definition at line 1324 of file vpCircleHoughTransform.h.

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

◆ 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 1327 of file vpCircleHoughTransform.h.

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

◆ m_fg

vpArray2D<float> vpCircleHoughTransform::m_fg
protected

Definition at line 1313 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 1338 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 1339 of file vpCircleHoughTransform.h.

Referenced by detect(), 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 1341 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 1340 of file vpCircleHoughTransform.h.

Referenced by detect(), and mergeCircleCandidates().

◆ m_gradientFilterX

vpArray2D<float> vpCircleHoughTransform::m_gradientFilterX
protected

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

Definition at line 1317 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 1318 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 1316 of file vpCircleHoughTransform.h.

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