#include <vpDetectorAprilTag.h>

Inheritance diagram for vpDetectorAprilTag:

Public Types
enum	vpAprilTagFamily { TAG_36h11 , TAG_36h10 , TAG_36ARTOOLKIT , TAG_25h9 , TAG_25h7 , TAG_16h5 , TAG_CIRCLE21h7 , TAG_CIRCLE49h12 , TAG_CUSTOM48h12 , TAG_STANDARD41h12 , TAG_STANDARD52h13 , TAG_ARUCO_4x4_50 , TAG_ARUCO_4x4_100 , TAG_ARUCO_4x4_250 , TAG_ARUCO_4x4_1000 , TAG_ARUCO_5x5_50 , TAG_ARUCO_5x5_100 , TAG_ARUCO_5x5_250 , TAG_ARUCO_5x5_1000 , TAG_ARUCO_6x6_50 , TAG_ARUCO_6x6_100 , TAG_ARUCO_6x6_250 , TAG_ARUCO_6x6_1000 , TAG_ARUCO_7x7_50 , TAG_ARUCO_7x7_100 , TAG_ARUCO_7x7_250 , TAG_ARUCO_7x7_1000 , TAG_ARUCO_MIP_36h12 }
enum	vpPoseEstimationMethod { HOMOGRAPHY , HOMOGRAPHY_VIRTUAL_VS , DEMENTHON_VIRTUAL_VS , LAGRANGE_VIRTUAL_VS , BEST_RESIDUAL_VIRTUAL_VS , HOMOGRAPHY_ORTHOGONAL_ITERATION }

Public Member Functions
	vpDetectorAprilTag (const vpAprilTagFamily &tagFamily=TAG_36h11, const vpPoseEstimationMethod &poseEstimationMethod=HOMOGRAPHY_VIRTUAL_VS)
	vpDetectorAprilTag (const vpDetectorAprilTag &o)
vpDetectorAprilTag &	operator= (vpDetectorAprilTag o)
virtual	~vpDetectorAprilTag () VP_OVERRIDE
bool	detect (const vpImage< unsigned char > &I) VP_OVERRIDE
bool	detect (const vpImage< unsigned char > &I, double tagSize, const vpCameraParameters &cam, std::vector< vpHomogeneousMatrix > &cMo_vec, std::vector< vpHomogeneousMatrix > cMo_vec2=nullptr, std::vector< double > projErrors=nullptr, std::vector< double > *projErrors2=nullptr)
void	displayFrames (const vpImage< unsigned char > &I, const std::vector< vpHomogeneousMatrix > &cMo_vec, const vpCameraParameters &cam, double size, const vpColor &color, unsigned int thickness=1) const
void	displayFrames (const vpImage< vpRGBa > &I, const std::vector< vpHomogeneousMatrix > &cMo_vec, const vpCameraParameters &cam, double size, const vpColor &color, unsigned int thickness=1) const
void	displayTags (const vpImage< unsigned char > &I, const std::vector< std::vector< vpImagePoint > > &tagsCorners, const vpColor &color=vpColor::none, unsigned int thickness=1) const
void	displayTags (const vpImage< vpRGBa > &I, const std::vector< std::vector< vpImagePoint > > &tagsCorners, const vpColor &color=vpColor::none, unsigned int thickness=1) const
float	getAprilTagDecisionMarginThreshold () const
int	getAprilTagHammingDistanceThreshold () const
bool	getPose (size_t tagIndex, double tagSize, const vpCameraParameters &cam, vpHomogeneousMatrix &cMo, vpHomogeneousMatrix cMo2=nullptr, double projError=nullptr, double *projError2=nullptr)
vpPoseEstimationMethod	getPoseEstimationMethod () const
bool	getTagImage (vpImage< unsigned char > &I, int id)
std::vector< std::vector< vpImagePoint > >	getTagsCorners () const
std::vector< float >	getTagsDecisionMargin () const
std::vector< int >	getTagsHammingDistance () const
std::vector< int >	getTagsId () const
std::vector< std::vector< vpPoint > >	getTagsPoints3D (const std::vector< int > &tagsId, const std::map< int, double > &tagsSize) const
bool	isZAlignedWithCameraAxis () const
void	setAprilTagDebugOption (bool flag)
void	setAprilTagDecisionMarginThreshold (float decisionMarginThreshold)
void	setAprilTagDecodeSharpening (double decodeSharpening)
void	setAprilTagFamily (const vpAprilTagFamily &tagFamily)
void	setAprilTagHammingDistanceThreshold (int hammingDistanceThreshold)
void	setAprilTagNbThreads (int nThreads)
void	setAprilTagPoseEstimationMethod (const vpPoseEstimationMethod &poseEstimationMethod)
void	setAprilTagQuadDecimate (float quadDecimate)
void	setAprilTagQuadSigma (float quadSigma)
void	setAprilTagRefineEdges (bool refineEdges)
void	setDisplayTag (bool display, const vpColor &color=vpColor::none, unsigned int thickness=2)
void	setZAlignedWithCameraAxis (bool zAlignedWithCameraFrame)

Friends
void	swap (vpDetectorAprilTag &o1, vpDetectorAprilTag &o2)

Deprecated functions
bool	m_displayTag
vpColor	m_displayTagColor
unsigned int	m_displayTagThickness
vpPoseEstimationMethod	m_poseEstimationMethod
vpAprilTagFamily	m_tagFamily
VP_DEPRECATED void	setAprilTagRefinePose (bool refinePose)
VP_DEPRECATED void	setAprilTagRefineDecode (bool refineDecode)

Inherited functionalities from vpDetectorBase
std::vector< std::vector< vpImagePoint > >	m_polygon
std::vector< std::string >	m_message
size_t	m_nb_objects
unsigned long	m_timeout_ms
vpRect	getBBox (size_t i) const
vpImagePoint	getCog (size_t i) const
std::vector< std::string > &	getMessage ()
std::string &	getMessage (size_t i)
size_t	getNbObjects () const
std::vector< std::vector< vpImagePoint > > &	getPolygon ()
std::vector< vpImagePoint > &	getPolygon (size_t i)
void	setTimeout (unsigned long timeout_ms)

Detailed Description

Base class for AprilTag detector. This class is a wrapper over AprilTag. There is no need to download and install AprilTag from source code or from existing pre-built packages since the source code is embedded in ViSP. Reference papers are AprilTag: A robust and flexible visual fiducial system ([42]), AprilTag 2: Efficient and robust fiducial detection ([58]) and Flexible Layouts for Fiducial Tags ([25]).

Supported tag families are the following:

AprilTag 16h5
AprilTag 25h9
AprilTag 36h10 (deprecated)
AprilTag 36h11
AprilTag Circle_21h7 (AprilTag 3)
AprilTag Circle_49h12 (AprilTag 3, CMake WITH_APRILTAG_BIG_FAMILY var must be set to true)
AprilTag Custom_48h12 (AprilTag 3, CMake WITH_APRILTAG_BIG_FAMILY var must be set to true)
AprilTag Standard_41h12 (AprilTag 3, CMake WITH_APRILTAG_BIG_FAMILY var must be set to true)
AprilTag Standard_52h13 (AprilTag 3, CMake WITH_APRILTAG_BIG_FAMILY var must be set to true)
ArUco 4x4
ArUco 5x5
ArUco 6x6
ArUco 7x7
ArUco MIP_36h12

Supported tags with id 0.

To use this class you can follow Tutorial: AprilTag/ArUco marker detection.

The detect() function allows to detect multiple tags in an image. Once detected, for each tag it is possible to retrieve the location of the corners using getPolygon(), the encoded message using getMessage(), the bounding box using getBBox() and the center of gravity using getCog().

If camera parameters and the size of the tag are provided, you can also estimate the 3D pose of the tag in terms of position and orientation wrt the camera considering 2 cases:

If all the tags have the same size use detect(const vpImage<unsigned char> &, double, const vpCameraParameters &, std::vector<vpHomogeneousMatrix> &, std::vector<vpHomogeneousMatrix> *, std::vector<double> *, std::vector<double> *)
If tag sizes differ, use rather getPose()

Note: With ViSP, the size of the tag corresponds to the black part of the tag. Note also that to be detected, the black part of the tag must be surrounded by a white border as wide as the black border as in the next image:

The following sample code shows how to use this class to detect the location of 36h11 AprilTag patterns in an image.

#include <visp3/detection/vpDetectorAprilTag.h>
#include <visp3/io/vpImageIo.h>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
int main()
{
#ifdef VISP_HAVE_APRILTAG
  vpImage<unsigned char> I;
  vpImageIo::read(I, "image-tag36h11.pgm");
 
  vpDetectorAprilTag detector(vpDetectorAprilTag::TAG_36h11);
 
  bool status = detector.detect(I);
  if (status) {
    for(size_t i=0; i < detector.getNbObjects(); ++i) {
      std::cout << "Tag code " << i << ":" << std::endl;
      std::vector<vpImagePoint> p = detector.getPolygon(i);
      for(size_t j=0; j < p.size(); ++j)
        std::cout << "  Point " << j << ": " << p[j] << std::endl;
      std::cout << "  Message: \"" << detector.getMessage(i) << "\"" << std::endl;
    }
  }
#endif
}

The previous example may produce results like:

Tag code 0:
  Point 0: 124.008, 442.226
  Point 1: 194.614, 441.237
  Point 2: 184.833, 540.386
  Point 3: 111.948, 533.634
  Message: "36h11 id: 0"
Tag code 1:
  Point 0: 245.327, 438.801
  Point 1: 338.116, 437.221
  Point 2: 339.341, 553.539
  Point 3: 238.954, 543.855
  Message: "36h11 id: 1"

As shown in the next image, two different tag frames could be considered for pose estimation.

Tag 36h11_00000 with location of the 4 corners and tag frame

There is the function setZAlignedWithCameraAxis() that allows to choose which tag frame has to be considered.

This other example shows how to estimate the 3D pose of 36h11 AprilTag patterns considering that all the tags have the same size (in our example 0.053 m). Here we consider the default case, when z-camera and z-tag axis are not aligned.

#include <visp3/detection/vpDetectorAprilTag.h>
#include <visp3/io/vpImageIo.h>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
int main()
{
#ifdef VISP_HAVE_APRILTAG
  vpImage<unsigned char> I;
  vpImageIo::read(I, "image-tag36h11.pgm");
 
  vpDetectorAprilTag detector(vpDetectorAprilTag::TAG_36h11);
  detector.setZAlignedWithCameraAxis(false); // Default configuration
  std::vector<vpHomogeneousMatrix> cMo;
  vpCameraParameters cam;
  cam.initPersProjWithoutDistortion(615.1674805, 615.1675415, 312.1889954, 243.4373779);
  double tagSize = 0.053;
 
  bool status = detector.detect(I, tagSize, cam, cMo);
  if (status) {
    for(size_t i=0; i < detector.getNbObjects(); ++i) {
      std::cout << "Tag number " << i << ":" << std::endl;
      std::cout << "  Message: \"" << detector.getMessage(i) << "\"" << std::endl;
      std::cout << "  Pose: " << vpPoseVector(cMo[i]).t() << std::endl;
      std::size_t tag_id_pos = detector.getMessage(i).find("id: ");
      if (tag_id_pos != std::string::npos) {
        std::string tag_id = detector.getMessage(i).substr(tag_id_pos + 4);
        std::cout << "  Tag Id: " << tag_id << std::endl;
      }
    }
  }
#endif
}

The previous example may produce results like:

Tag number 0:
  Message: "36h11 id: 0"
  Pose: 0.1015061088  -0.05239057228  0.3549037285  1.991474322  2.04143538 -0.9412360063
  Tag Id: 0
Tag number 1:
  Message: "36h11 id: 1"
  Pose: 0.08951250829 0.02243780207  0.306540622  1.998073197  2.061488008  -0.8699567948
  Tag Id: 1

In this other example we estimate the 3D pose of 36h11 AprilTag patterns considering that tag 36h11 with id 0 (in that case the tag message is "36h11 id: 0") has a size of 0.040 m, while all the others have a size of 0.053m.

#include <visp3/detection/vpDetectorAprilTag.h>
#include <visp3/io/vpImageIo.h>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
int main()
{
#ifdef VISP_HAVE_APRILTAG
  vpImage<unsigned char> I;
  vpImageIo::read(I, "image-tag36h11.pgm");
 
  vpDetectorAprilTag detector(vpDetectorAprilTag::TAG_36h11);
  vpHomogeneousMatrix cMo;
  vpCameraParameters cam;
  cam.initPersProjWithoutDistortion(615.1674805, 615.1675415, 312.1889954, 243.4373779);
  double tagSize_id_0 = 0.04;
  double tagSize_id_others = 0.053;
 
  bool status = detector.detect(I);
  if (status) {
    for(size_t i=0; i < detector.getNbObjects(); ++i) {
      std::cout << "Tag code " << i << ":" << std::endl;
      std::cout << "  Message: \"" << detector.getMessage(i) << "\"" << std::endl;
      if (detector.getMessage(i) == std::string("36h11 id: 0")) {
        if (! detector.getPose(i, tagSize_id_0, cam, cMo)) {
          std::cout << "Unable to get tag index " << i << " pose!" << std::endl;
        }
      }
      else {
        if (! detector.getPose(i, tagSize_id_others, cam, cMo)) {
          std::cout << "Unable to get tag index " << i << " pose!" << std::endl;
        }
      }
      std::cout << "  Pose: " << vpPoseVector(cMo).t() << std::endl;
    }
  }
#endif
}

With respect to the previous example, this example may now produce a different pose for tag with id 0:

Tag code 0:
  Message: "36h11 id: 0"
  Pose: 0.07660838403  -0.03954005455  0.2678518706  1.991474322  2.04143538  -0.9412360063
Tag code 1:
  Message: "36h11 id: 1"
  Pose: 0.08951250829  0.02243780207  0.306540622  1.998073197  2.061488008  -0.8699567948

Tutorials & Examples

Tutorials
If you want a detailed explanation on how to use this class, you may have a look at:

Tutorial: AprilTag/ArUco marker detection

Examples: catchAprilTag.cpp, catchArUco.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, mbot-apriltag-pbvs.cpp, perfApriltagDetection.cpp, servoAfma6AprilTagIBVS.cpp, servoAfma6AprilTagPBVS.cpp, servoBebop2.cpp, servoBiclopsPoint2DArtVelocity.cpp, servoFlirPtuIBVS.cpp, servoFrankaIBVS-EyeToHand-Lcur_cVe_eJe.cpp, servoFrankaIBVS-EyeToHand-Lcur_cVf_fVe_eJe.cpp, servoFrankaIBVS-EyeToHand-Ldes_cVf_fVe_eJe.cpp, servoFrankaIBVS.cpp, servoFrankaPBVS.cpp, servoPixhawkDroneIBVS.cpp, servoPololuPtuPoint2DJointVelocity.cpp, servoUniversalRobotsIBVS.cpp, servoUniversalRobotsPBVS.cpp, tutorial-apriltag-detector-live-T265-realsense.cpp, tutorial-apriltag-detector-live-rgbd-realsense.cpp, tutorial-apriltag-detector-live-rgbd-structure-core.cpp, tutorial-apriltag-detector-live.cpp, tutorial-apriltag-detector.cpp, tutorial-create-tag-image.cpp, tutorial-flir-ptu-ibvs.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, tutorial-mb-generic-tracker-apriltag-webcam.cpp, and visp-compute-apriltag-poses.cpp.

Definition at line 261 of file vpDetectorAprilTag.h.

Member Enumeration Documentation

◆ vpAprilTagFamily

enum vpDetectorAprilTag::vpAprilTagFamily

Enumerator
TAG_36h11	AprilTag 36h11 pattern (recommended).
TAG_36h10	DEPRECATED.
TAG_36ARTOOLKIT	DEPRECATED AND WILL NOT DETECT ARTOOLKIT TAGS.
TAG_25h9	AprilTag 25h9 pattern.
TAG_25h7	DEPRECATED AND POOR DETECTION PERFORMANCE.
TAG_16h5	AprilTag 16h5 pattern.
TAG_CIRCLE21h7	AprilTag Circle21h7 pattern.
TAG_CIRCLE49h12	AprilTag Circle49h12 pattern.
TAG_CUSTOM48h12	AprilTag Custom48h12 pattern.
TAG_STANDARD41h12	AprilTag Standard41h12 pattern.
TAG_STANDARD52h13	AprilTag Standard52h13 pattern.
TAG_ARUCO_4x4_50	ArUco 4x4 pattern: 4x4 bits, minimum hamming distance between any two codes = 4, 50 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_4x4_100	ArUco 4x4 pattern: 4x4 bits, minimum hamming distance between any two codes = 3, 100 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_4x4_250	ArUco 4x4 pattern: 4x4 bits, minimum hamming distance between any two codes = 3, 250 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_4x4_1000	ArUco 4x4 pattern: 4x4 bits, minimum hamming distance between any two codes = 2, 1000 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_5x5_50	ArUco 5x5 pattern: 5x5 bits, minimum hamming distance between any two codes = 8, 50 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_5x5_100	ArUco 5x5 pattern: 5x5 bits, minimum hamming distance between any two codes = 7, 100 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_5x5_250	ArUco 5x5 pattern: 5x5 bits, minimum hamming distance between any two codes = 6, 250 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_5x5_1000	ArUco 5x5 pattern: 5x5 bits, minimum hamming distance between any two codes = 5, 1000 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_6x6_50	ArUco 6x6 pattern: 6x6 bits, minimum hamming distance between any two codes = 13, 50 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_6x6_100	ArUco 6x6 pattern: 6x6 bits, minimum hamming distance between any two codes = 12, 100 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_6x6_250	ArUco 6x6 pattern: 6x6 bits, minimum hamming distance between any two codes = 11, 250 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_6x6_1000	ArUco 6x6 pattern: 6x6 bits, minimum hamming distance between any two codes = 9, 1000 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_7x7_50	ArUco 7x7 pattern: 7x7 bits, minimum hamming distance between any two codes = 19, 50 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_7x7_100	ArUco 7x7 pattern: 7x7 bits, minimum hamming distance between any two codes = 18, 100 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_7x7_250	ArUco 7x7 pattern: 7x7 bits, minimum hamming distance between any two codes = 17, 250 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_7x7_1000	ArUco 7x7 pattern: 7x7 bits, minimum hamming distance between any two codes = 14, 1000 codes. This tag family can produce lots of false detections which can be filtered by setting an appropriate decision margin, using setAprilTagDecisionMarginThreshold() or getTagsDecisionMargin(). See 4.1. Filter out false positive detections section for more details.
TAG_ARUCO_MIP_36h12	ArUco 6x6 pattern: 6x6 bits, minimum hamming distance between any two codes = 12, 250 codes. This is the recommended ArUco tag family by the main ArUco developer, see this link

Examples: catchAprilTag.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, mbot-apriltag-pbvs.cpp, servoAfma6AprilTagIBVS.cpp, servoAfma6AprilTagPBVS.cpp, servoBebop2.cpp, servoFlirPtuIBVS.cpp, servoFrankaIBVS-EyeToHand-Lcur_cVe_eJe.cpp, servoFrankaIBVS-EyeToHand-Lcur_cVf_fVe_eJe.cpp, servoFrankaIBVS-EyeToHand-Ldes_cVf_fVe_eJe.cpp, servoFrankaIBVS.cpp, servoFrankaPBVS.cpp, servoPixhawkDroneIBVS.cpp, servoUniversalRobotsIBVS.cpp, servoUniversalRobotsPBVS.cpp, tutorial-apriltag-detector-live-T265-realsense.cpp, tutorial-apriltag-detector-live-rgbd-realsense.cpp, tutorial-apriltag-detector-live-rgbd-structure-core.cpp, tutorial-apriltag-detector-live.cpp, tutorial-apriltag-detector.cpp, tutorial-create-tag-image.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, tutorial-mb-generic-tracker-apriltag-webcam.cpp, and visp-compute-apriltag-poses.cpp.

Definition at line 264 of file vpDetectorAprilTag.h.

◆ vpPoseEstimationMethod

enum vpDetectorAprilTag::vpPoseEstimationMethod

Enumerator
HOMOGRAPHY	Pose from homography
HOMOGRAPHY_VIRTUAL_VS	Non linear virtual visual servoing approach initialized by the homography approach
DEMENTHON_VIRTUAL_VS	Non linear virtual visual servoing approach initialized by the Dementhon approach
LAGRANGE_VIRTUAL_VS	Non linear virtual visual servoing approach initialized by the Lagrange approach
BEST_RESIDUAL_VIRTUAL_VS	Non linear virtual visual servoing approach initialized by the approach that gives the lowest residual
HOMOGRAPHY_ORTHOGONAL_ITERATION	Pose from homography followed by a refinement by Orthogonal Iteration

Examples: catchAprilTag.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-pbvs.cpp, servoAfma6AprilTagIBVS.cpp, servoAfma6AprilTagPBVS.cpp, servoFlirPtuIBVS.cpp, servoFrankaIBVS-EyeToHand-Lcur_cVe_eJe.cpp, servoFrankaIBVS-EyeToHand-Lcur_cVf_fVe_eJe.cpp, servoFrankaIBVS-EyeToHand-Ldes_cVf_fVe_eJe.cpp, servoFrankaIBVS.cpp, servoFrankaPBVS.cpp, servoUniversalRobotsIBVS.cpp, servoUniversalRobotsPBVS.cpp, tutorial-apriltag-detector-live-T265-realsense.cpp, tutorial-apriltag-detector-live-rgbd-realsense.cpp, tutorial-apriltag-detector-live-rgbd-structure-core.cpp, tutorial-apriltag-detector-live.cpp, tutorial-apriltag-detector.cpp, and visp-compute-apriltag-poses.cpp.

Definition at line 346 of file vpDetectorAprilTag.h.

Constructor & Destructor Documentation

◆ vpDetectorAprilTag() [1/2]

BEGIN_VISP_NAMESPACE vpDetectorAprilTag::vpDetectorAprilTag	(	const vpAprilTagFamily &	tagFamily = TAG_36h11,
		const vpPoseEstimationMethod &	poseEstimationMethod = HOMOGRAPHY_VIRTUAL_VS )

Definition at line 1169 of file vpDetectorAprilTag.cpp.

References m_displayTag, m_displayTagColor, m_displayTagThickness, m_poseEstimationMethod, and m_tagFamily.

Referenced by operator=(), swap, and vpDetectorAprilTag().

◆ vpDetectorAprilTag() [2/2]

vpDetectorAprilTag::vpDetectorAprilTag ( const vpDetectorAprilTag & o )

Definition at line 1176 of file vpDetectorAprilTag.cpp.

References m_displayTag, m_displayTagColor, m_displayTagThickness, m_poseEstimationMethod, m_tagFamily, vpDetectorAprilTag(), and vpDetectorBase::vpDetectorBase().

◆ ~vpDetectorAprilTag()

vpDetectorAprilTag::~vpDetectorAprilTag ( )

virtual

Definition at line 1188 of file vpDetectorAprilTag.cpp.

Member Function Documentation

◆ detect() [1/2]

bool vpDetectorAprilTag::detect ( const vpImage< unsigned char > & I )

virtual

Detect AprilTag tags in the image. Return true if at least one tag is detected, false otherwise.

Parameters

I	: Input image.

Returns: true if at least one tag is detected.

Implements vpDetectorBase.

Examples: catchAprilTag.cpp, catchArUco.cpp, perfApriltagDetection.cpp, servoBiclopsPoint2DArtVelocity.cpp, servoPololuPtuPoint2DJointVelocity.cpp, tutorial-flir-ptu-ibvs.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, and tutorial-mb-generic-tracker-apriltag-webcam.cpp.

Definition at line 1197 of file vpDetectorAprilTag.cpp.

References m_displayTag, m_displayTagColor, m_displayTagThickness, vpDetectorBase::m_message, vpDetectorBase::m_nb_objects, and vpDetectorBase::m_polygon.

Referenced by visp.python.rbt.xfeat.XFeatTrackingBackend.XFeatTrackingBackend::process_frame().

◆ detect() [2/2]

bool vpDetectorAprilTag::detect	(	const vpImage< unsigned char > &	I,
		double	tagSize,
		const vpCameraParameters &	cam,
		std::vector< vpHomogeneousMatrix > &	cMo_vec,
		std::vector< vpHomogeneousMatrix > *	cMo_vec2 = nullptr,
		std::vector< double > *	projErrors = nullptr,
		std::vector< double > *	projErrors2 = nullptr )

Detect AprilTag tags in the image and compute the corresponding tag poses considering that all the tags have the same size.

If tags with different sizes have to be considered, you may use getPose().

Parameters

[in]	I	: Input image.
[in]	tagSize	: Tag size in meter corresponding to the external width of the pattern.
[in]	cam	: Camera intrinsic parameters.
[out]	cMo_vec	: List of tag poses.
[out]	cMo_vec2	: Optional second list of tag poses, since there are 2 solutions for planar pose estimation.
[out]	projErrors	: Optional (sum of squared) projection errors in the normalized camera frame.
[out]	projErrors2	: Optional (sum of squared) projection errors for the 2nd solution in the normalized camera frame.

Returns: true if at least one tag is detected.

See also: getPose()

Definition at line 1229 of file vpDetectorAprilTag.cpp.

References m_displayTag, m_displayTagColor, m_displayTagThickness, vpDetectorBase::m_message, vpDetectorBase::m_nb_objects, and vpDetectorBase::m_polygon.

Referenced by visp.python.rbt.xfeat.XFeatTrackingBackend.XFeatTrackingBackend::process_frame().

◆ displayFrames() [1/2]

void vpDetectorAprilTag::displayFrames	(	const vpImage< unsigned char > &	I,
		const std::vector< vpHomogeneousMatrix > &	cMo_vec,
		const vpCameraParameters &	cam,
		double	size,
		const vpColor &	color,
		unsigned int	thickness = 1 ) const

Display the tag frames on a grayscale image.

Parameters

[in]	I	: The image.
[in]	cMo_vec	: The vector of computed tag poses.
[in]	cam	: Camera intrinsic parameters.
[out]	size	: Size of the frame.
[out]	color	: The desired color, if none the X-axis is red, the Y-axis green and the Z-axis blue.
[out]	thickness	: The thickness of the lines.

Definition at line 1258 of file vpDetectorAprilTag.cpp.

◆ displayFrames() [2/2]

void vpDetectorAprilTag::displayFrames	(	const vpImage< vpRGBa > &	I,
		const std::vector< vpHomogeneousMatrix > &	cMo_vec,
		const vpCameraParameters &	cam,
		double	size,
		const vpColor &	color,
		unsigned int	thickness = 1 ) const

Display the tag frames on a vpRGBa image.

Parameters

[in]	I	: The image.
[in]	cMo_vec	: The vector of computed tag poses.
[in]	cam	: Camera intrinsic parameters.
[out]	size	: Size of the frame.
[out]	color	: The desired color, if none the X-axis is red, the Y-axis green and the Z-axis blue.
[out]	thickness	: The thickness of the lines.

Definition at line 1274 of file vpDetectorAprilTag.cpp.

◆ displayTags() [1/2]

void vpDetectorAprilTag::displayTags	(	const vpImage< unsigned char > &	I,
		const std::vector< std::vector< vpImagePoint > > &	tagsCorners,
		const vpColor &	color = vpColor::none,
		unsigned int	thickness = 1 ) const

Display the tag contours on a grayscale image.

Parameters

[in]	I	: The image.
[in]	tagsCorners	: The vector of tag contours.
[out]	color	: The desired color, if none RGBY colors are used.
[out]	thickness	: The thickness of the lines.

Definition at line 1288 of file vpDetectorAprilTag.cpp.

◆ displayTags() [2/2]

void vpDetectorAprilTag::displayTags	(	const vpImage< vpRGBa > &	I,
		const std::vector< std::vector< vpImagePoint > > &	tagsCorners,
		const vpColor &	color = vpColor::none,
		unsigned int	thickness = 1 ) const

Display the tag contours on a vpRGBa image.

Parameters

[in]	I	: The image.
[in]	tagsCorners	: The vector of tag contours.
[out]	color	: The desired color, if none RGBY colors are used.
[out]	thickness	: The thickness of the lines.

Definition at line 1302 of file vpDetectorAprilTag.cpp.

◆ getAprilTagDecisionMarginThreshold()

float vpDetectorAprilTag::getAprilTagDecisionMarginThreshold ( ) const

Get the decision margin threshold to filter out false detections. Higher is the decision margin for each detected tag, better is the detection. When the decision margin threshold is equal to -1, tags decision margin values are not used to filter potential false positive detection.

See also: setAprilTagDecisionMarginThreshold(), setAprilTagHammingDistanceThreshold()

Examples: catchArUco.cpp.

Definition at line 1417 of file vpDetectorAprilTag.cpp.

◆ getAprilTagHammingDistanceThreshold()

int vpDetectorAprilTag::getAprilTagHammingDistanceThreshold ( ) const

Get the hamming distance threshold to filter out false detections. For each tag detected, the hamming distance is between 0 and 255 and indicates the number of bit-error that are corrected. A value of 0 indicates that no correction was applied when the tag was detected, while a value of 2 indicates that 2 bits were corrected to achieve detection. The lower the Hamming distance, the more reliable the detection.

Default value is 2, meaning that we don't filter out detections with corrected bits.

This threshold could be used to filter out detections where the hamming distance is greater than this threshold.

See also: setAprilTagHammingDistanceThreshold(), setAprilTagDecisionMarginThreshold()

Examples: catchArUco.cpp.

Definition at line 1435 of file vpDetectorAprilTag.cpp.

◆ getBBox()

vpRect vpDetectorBase::getBBox ( size_t i ) const

inherited

Return the bounding box of the ith object.

Examples: tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 92 of file vpDetectorBase.cpp.

References m_polygon.

Referenced by detect().

◆ getCog()

vpImagePoint vpDetectorBase::getCog ( size_t i ) const

inherited

Return the center of gravity location of the ith object.

Examples: servoBiclopsPoint2DArtVelocity.cpp, servoPololuPtuPoint2DJointVelocity.cpp, and tutorial-flir-ptu-ibvs.cpp.

Definition at line 78 of file vpDetectorBase.cpp.

References m_polygon.

Referenced by detect().

◆ getMessage() [1/2]

std::vector< std::string > & vpDetectorBase::getMessage ( )

inlineinherited

Returns the contained message of the ith object if there is one.

Examples: catchAprilTag.cpp, catchArUco.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 98 of file vpDetectorBase.h.

References m_message.

◆ getMessage() [2/2]

std::string & vpDetectorBase::getMessage ( size_t i )

inherited

Returns the contained message of the ith object if there is one.

Definition at line 64 of file vpDetectorBase.cpp.

References vpException::badValue, m_message, and m_polygon.

◆ getNbObjects()

size_t vpDetectorBase::getNbObjects ( ) const

inlineinherited

Return the number of objects that are detected.

Examples: catchAprilTag.cpp, catchArUco.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live.cpp, tutorial-face-detector.cpp, tutorial-flir-ptu-ibvs.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, tutorial-mb-generic-tracker-apriltag-webcam.cpp, and tutorial-pose-from-qrcode-image.cpp.

Definition at line 108 of file vpDetectorBase.h.

References m_nb_objects.

◆ getPolygon() [1/2]

std::vector< std::vector< vpImagePoint > > & vpDetectorBase::getPolygon ( )

inlineinherited

Returns object container box as a vector of points.

Examples: catchAprilTag.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, and tutorial-pose-from-qrcode-image.cpp.

Definition at line 113 of file vpDetectorBase.h.

References m_polygon.

◆ getPolygon() [2/2]

std::vector< vpImagePoint > & vpDetectorBase::getPolygon ( size_t i )

inherited

Returns ith object container box as a vector of points.

Definition at line 50 of file vpDetectorBase.cpp.

References vpException::badValue, and m_polygon.

◆ getPose()

bool vpDetectorAprilTag::getPose	(	size_t	tagIndex,
		double	tagSize,
		const vpCameraParameters &	cam,
		vpHomogeneousMatrix &	cMo,
		vpHomogeneousMatrix *	cMo2 = nullptr,
		double *	projError = nullptr,
		double *	projError2 = nullptr )

Get the pose of a tag depending on its size and camera parameters. This function is useful to get the pose of tags with different sizes, while detect(const vpImage<unsigned char> &, const double, const vpCameraParameters &, std::vector<vpHomogeneousMatrix> &) considers that all the tags have the same size.

Parameters

[in]	tagIndex	: Index of the tag. Value should be in range [0, nb tags-1] with nb_tags = getNbObjects(). Note that this index doesn't correspond to the tag id.
[in]	tagSize	: Tag size in meter corresponding to the external width of the pattern.
[in]	cam	: Camera intrinsic parameters.
[out]	cMo	: Pose of the tag.
[out]	cMo2	: Optional second pose of the tag.
[out]	projError	: Optional (sum of squared) projection errors in the normalized camera frame.
[out]	projError2	: Optional (sum of squared) projection errors for the 2nd solution in the normalized camera frame.

Returns: true if success, false otherwise.

The following code shows how to use this function:

vpCameraParameters cam;
vpDetectorAprilTag detector(vpDetectorAprilTag::TAG_36h11);
detector.detect(I);
for (size_t i = 0; i < detector.getNbObjects(); i++) {
  vpHomogeneousMatrix cMo;
  double tagSize = 0.1;
  detector.getPose(i, tagSize, cam, cMo);
}

See also: detect(const vpImage<unsigned char> &, double, const vpCameraParameters &, std::vector<vpHomogeneousMatrix> *, std::vector<vpHomogeneousMatrix> *, std::vector<double> *, std::vector<double> *)

Examples: catchAprilTag.cpp.

Definition at line 1339 of file vpDetectorAprilTag.cpp.

◆ getPoseEstimationMethod()

vpPoseEstimationMethod vpDetectorAprilTag::getPoseEstimationMethod ( ) const

inline

Return the pose estimation method.

Definition at line 390 of file vpDetectorAprilTag.h.

References getPoseEstimationMethod(), and m_poseEstimationMethod.

Referenced by getPoseEstimationMethod().

◆ getTagImage()

bool vpDetectorAprilTag::getTagImage	(	vpImage< unsigned char > &	I,
		int	id )

Create an image of a marker corresponding to the current tag family with a given id.

Parameters

[out]	I	: Image with the created marker.
[in]	id	: Marker id.

Returns: true when image created successfully, false otherwise.

Examples: catchArUco.cpp.

Definition at line 1474 of file vpDetectorAprilTag.cpp.

◆ getTagsCorners()

std::vector< std::vector< vpImagePoint > > vpDetectorAprilTag::getTagsCorners ( ) const

Return the corners coordinates for the detected tags.

See also: getTagsId(), getTagsPoints3D()

Examples: catchAprilTag.cpp.

Definition at line 1445 of file vpDetectorAprilTag.cpp.

References vpDetectorBase::m_polygon.

◆ getTagsDecisionMargin()

std::vector< float > vpDetectorAprilTag::getTagsDecisionMargin ( ) const

Return the decision marging for each detection. It could be seen as a quality detection indicator. The higher the value, the greater the confidence in detection.

Note: When the decision margin threshold set using setAprilTagDecisionMargin() differs from -1, this decision margin is used internally to filter out false detections.

See also: getTagsCorners(), getTagsPoints3D(), getTagsId(), getTagsHammingDistance(), setAprilTagDecisionMargin()

Examples: catchArUco.cpp.

Definition at line 1488 of file vpDetectorAprilTag.cpp.

◆ getTagsHammingDistance()

std::vector< int > vpDetectorAprilTag::getTagsHammingDistance ( ) const

Return the hamming distance for each detection in range 0 - 255. This hamming distance corresponds to the number of bits that were corrected. Having values greater than 0 leads to greatly increased false positive rates. Thus it could be seen as a quality detection indicator.

Note: As of this implementation, the detector cannot detect tags with a hamming distance greater than 2.

See also: getTagsCorners(), getTagsPoints3D(), getTagsId(), getTagsDecisionMargin()

Examples: catchArUco.cpp.

Definition at line 1500 of file vpDetectorAprilTag.cpp.

◆ getTagsId()

std::vector< int > vpDetectorAprilTag::getTagsId ( ) const

Return the decoded Apriltag id for each detection.

See also: getTagsCorners(), getTagsPoints3D(), getTagsDecisionMargin(), getTagsHammingDistance()

Examples: catchAprilTag.cpp, and catchArUco.cpp.

Definition at line 1507 of file vpDetectorAprilTag.cpp.

◆ getTagsPoints3D()

std::vector< std::vector< vpPoint > > vpDetectorAprilTag::getTagsPoints3D	(	const std::vector< int > &	tagsId,
		const std::map< int, double > &	tagsSize ) const

Return a vector that contains for each tag id the corresponding tag 3D corners coordinates in the tag frame.

Parameters

tagsId : A vector containing the id of each tag that is detected. It's size corresponds to the number of tags that are detected. This vector is returned by getTagsId().

tagsSize

: a map that contains as first element a tag id and as second elements its 3D size in meter. When first element of this map is -1, the second element corresponds to the default tag size.

std::map<int, double> tagsSize;
tagsSize[-1] = 0.05; // Default tag size in meter, used when detected tag id is not in this map
tagsSize[10] = 0.1;  // All tags with id 10 are 0.1 meter large
tagsSize[20] = 0.2;  // All tags with id 20 are 0.2 meter large

See also: getTagsCorners(), getTagsId()

Examples: catchAprilTag.cpp.

Definition at line 1363 of file vpDetectorAprilTag.cpp.

References vpException::fatalError.

◆ isZAlignedWithCameraAxis()

bool vpDetectorAprilTag::isZAlignedWithCameraAxis ( ) const

Indicate it z-axis of the tag frame is aligned with the camera frame or not.

Returns: When true, z-axis are aligned, false otherwise

Definition at line 1696 of file vpDetectorAprilTag.cpp.

◆ operator=()

vpDetectorAprilTag & vpDetectorAprilTag::operator= ( vpDetectorAprilTag o )

Definition at line 1182 of file vpDetectorAprilTag.cpp.

References swap, and vpDetectorAprilTag().

◆ setAprilTagDebugOption()

void vpDetectorAprilTag::setAprilTagDebugOption ( bool flag )

Using this option allows debugging the AprilTag marker detection process. This can be used to understand why a marker is not detected for instance.

It will generate in the exe folder different debugging images, among others:

'debug_preprocess.pnm' corresponding to 'decimation, sharp/blur' preprocessing
'debug_threshold.pnm' corresponding to 'step 1. threshold the image, creating the edge image.'
'debug_segmentation.pnm' corresponding to 'step 2. find connected components.'
'debug_clusters.pnm' corresponding to the 'gradient_clusters()' function
'debug_quads_raw.pnm' corresponding to the detected quad shapes
'debug_samples.pnm' corresponding to the successfully decoded quad
'debug_output.pnm' corresponding to the final output after post-processing (non-overlapping duplicate detections)

Parameters

[in] flag : Debug flag.

Definition at line 1462 of file vpDetectorAprilTag.cpp.

◆ setAprilTagDecisionMarginThreshold()

void vpDetectorAprilTag::setAprilTagDecisionMarginThreshold ( float decisionMarginThreshold )

See the AprilTag documentation:

A measure of the quality of the binary decoding process: the average difference between the intensity of a data bit versus the decision threshold. Higher numbers roughly indicate better decodes. This is a reasonable measure of detection accuracy only for very small tags– not effective for larger tags (where we could have sampled anywhere within a bit cell and still gotten a good detection.)

It has been experimentally observed that using the AprilTag detection and decoding pipeline, lots of false positives arise with 16h5, 4x4, 5x5, 6x6 and 7x7 ArUco dictionnaries. A decision margin threshold can be used to filter these detections.

Parameters

[in]

decisionMarginThreshold

: Decision margin threshold used to filter false positive detections.

When this threshold is set to -1, the decision margin threshold is not used to eliminate detections whose detection margin is lower than this threshold.
When set, we recommand a value of 100 that makes especially 16h5, 4x4, 5x5, 6x6 and 7x7 ArUco families detection more reliable.
Default value is set to -1.

See also: getAprilTagDecisionMarginThreshold(), getTagsDecisionMargin()

Examples: catchArUco.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, and tutorial-mb-generic-tracker-apriltag-webcam.cpp.

Definition at line 1537 of file vpDetectorAprilTag.cpp.

◆ setAprilTagDecodeSharpening()

void vpDetectorAprilTag::setAprilTagDecodeSharpening ( double decodeSharpening )

Definition at line 1509 of file vpDetectorAprilTag.cpp.

◆ setAprilTagFamily()

void vpDetectorAprilTag::setAprilTagFamily ( const vpAprilTagFamily & tagFamily )

Definition at line 1569 of file vpDetectorAprilTag.cpp.

References m_poseEstimationMethod.

◆ setAprilTagHammingDistanceThreshold()

void vpDetectorAprilTag::setAprilTagHammingDistanceThreshold ( int hammingDistanceThreshold )

See the AprilTag documentation:

How many error bits were corrected? Note: accepting large numbers of corrected errors leads to greatly increased false positive rates. NOTE: As of this implementation, the detector cannot detect tags with a hamming distance greater than 2.

It has been experimentally observed that using the AprilTag detection and decoding pipeline, lots of false positives arise with 16h5, 4x4, 5x5, 6x6 and 7x7 ArUco dictionnaries. Their hamming distance is than usually set to 2. A hamming distance threshold can be used to filter these detections using setAprilTagHammingDistanceThreshold().

Parameters

[in]

hammingDistanceThreshold

: Threshold between 0 and 255 used to filter tags whose hamming distance is greater than this threshold.

When this threshold is set to 0, only tags for which no bits are corrected are detected.
When set to 2, it means that we keep all the tags that have up to 2 corrected bits. It will lead to false positive detections.
Default value is set to 2.

See also: getAprilTagDecisionMarginThreshold(), getTagsDecisionMargin()

Examples: catchArUco.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, and tutorial-mb-generic-tracker-apriltag-webcam.cpp.

Definition at line 1563 of file vpDetectorAprilTag.cpp.

◆ setAprilTagNbThreads()

void vpDetectorAprilTag::setAprilTagNbThreads ( int nThreads )

Set the number of threads for April Tag detection (default is 1).

Parameters

nThreads : Number of thread.

Examples: perfApriltagDetection.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, and tutorial-mb-generic-tracker-apriltag-webcam.cpp.

Definition at line 1599 of file vpDetectorAprilTag.cpp.

◆ setAprilTagPoseEstimationMethod()

void vpDetectorAprilTag::setAprilTagPoseEstimationMethod ( const vpPoseEstimationMethod & poseEstimationMethod )

Set the method to use to compute the pose,

See also: vpPoseEstimationMethod

Parameters

poseEstimationMethod : The method to used.

Examples: tutorial-flir-ptu-ibvs.cpp.

Definition at line 1611 of file vpDetectorAprilTag.cpp.

References m_poseEstimationMethod.

◆ setAprilTagQuadDecimate()

void vpDetectorAprilTag::setAprilTagQuadDecimate ( float quadDecimate )

From the AprilTag code:

detection of quads can be done on a lower-resolution image, improving speed at a cost of pose accuracy and a slight decrease in detection rate. Decoding the binary payload is still done at full resolution.

Default is 1.0, increase this value to reduce the computation time.

Parameters

quadDecimate : Value for quad_decimate.

Examples: catchAprilTag.cpp, perfApriltagDetection.cpp, tutorial-flir-ptu-ibvs.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, and tutorial-mb-generic-tracker-apriltag-webcam.cpp.

Definition at line 1629 of file vpDetectorAprilTag.cpp.

◆ setAprilTagQuadSigma()

void vpDetectorAprilTag::setAprilTagQuadSigma ( float quadSigma )

From the AprilTag code:

What Gaussian blur should be applied to the segmented image (used for quad detection?) Parameter is the standard deviation in pixels. Very noisy images benefit from non-zero values (e.g. 0.8).

Default is 0.0.

Parameters

quadSigma : Value for quad_sigma.

Examples: perfApriltagDetection.cpp.

Definition at line 1643 of file vpDetectorAprilTag.cpp.

◆ setAprilTagRefineDecode()

void vpDetectorAprilTag::setAprilTagRefineDecode ( bool refineDecode )

Deprecated: Deprecated parameter from AprilTag 2 version.

Definition at line 1649 of file vpDetectorAprilTag.cpp.

◆ setAprilTagRefineEdges()

void vpDetectorAprilTag::setAprilTagRefineEdges ( bool refineEdges )

From the AprilTag code:

When non-zero, the edges of the each quad are adjusted to "snap to" strong gradients nearby. This is useful when decimation is employed, as it can increase the quality of the initial quad estimate substantially. Generally recommended to be on (1). Very computationally inexpensive. Option is ignored if quad_decimate = 1.

Default is 1.

Parameters

refineEdges : If true, set refine edges parameter.

Definition at line 1669 of file vpDetectorAprilTag.cpp.

◆ setAprilTagRefinePose()

void vpDetectorAprilTag::setAprilTagRefinePose ( bool refinePose )

Deprecated: Deprecated parameter from AprilTag 2 version.

Definition at line 1675 of file vpDetectorAprilTag.cpp.

◆ setDisplayTag()

void vpDetectorAprilTag::setDisplayTag	(	bool	display,
		const vpColor &	color = vpColor::none,
		unsigned int	thickness = 2 )

inline

Allow to enable the display of overlay tag information in the windows (vpDisplay) associated to the input image.

Examples: tutorial-flir-ptu-ibvs.cpp.

Definition at line 416 of file vpDetectorAprilTag.h.

References m_displayTag, m_displayTagColor, m_displayTagThickness, and vpColor::none.

◆ setTimeout()

void vpDetectorBase::setTimeout ( unsigned long timeout_ms )

inlineinherited

Set detector timeout in milli-seconds. When set to 0, there is no timeout.

Definition at line 123 of file vpDetectorBase.h.

References m_timeout_ms.

Referenced by vpDetectorDataMatrixCode::vpDetectorDataMatrixCode().

◆ setZAlignedWithCameraAxis()

void vpDetectorAprilTag::setZAlignedWithCameraAxis ( bool zAlignedWithCameraFrame )

Modify the resulting tag pose returned by getPose() or detect(const vpImage<unsigned char> &, double, const vpCameraParameters &, std::vector<vpHomogeneousMatrix> &, std::vector<vpHomogeneousMatrix> *, std::vector<double> *, std::vector<double> *) in order to get a pose where z-axis is aligned when the camera plane is parallel to the tag.

Tag 36h11_00000 with location of the 4 corners and tag frame

Parameters

zAlignedWithCameraFrame : When set to true, estimated tag pose has a z-axis aligned with the camera frame.

Definition at line 1687 of file vpDetectorAprilTag.cpp.

◆ swap

void swap	(	vpDetectorAprilTag &	o1,
		vpDetectorAprilTag &	o2 )

friend

Definition at line 423 of file vpDetectorAprilTag.h.

References swap, and vpDetectorAprilTag().

Referenced by operator=(), and swap.

Member Data Documentation

◆ m_displayTag

bool vpDetectorAprilTag::m_displayTag

protected

Definition at line 442 of file vpDetectorAprilTag.h.

Referenced by detect(), detect(), setDisplayTag(), vpDetectorAprilTag(), and vpDetectorAprilTag().

◆ m_displayTagColor

vpColor vpDetectorAprilTag::m_displayTagColor

protected

Definition at line 443 of file vpDetectorAprilTag.h.

Referenced by detect(), detect(), setDisplayTag(), vpDetectorAprilTag(), and vpDetectorAprilTag().

◆ m_displayTagThickness

unsigned int vpDetectorAprilTag::m_displayTagThickness

protected

Definition at line 444 of file vpDetectorAprilTag.h.

Referenced by detect(), detect(), setDisplayTag(), vpDetectorAprilTag(), and vpDetectorAprilTag().

◆ m_message

std::vector<std::string> vpDetectorBase::m_message

protectedinherited

Message attached to each object.

Definition at line 129 of file vpDetectorBase.h.

Referenced by vpDetectorAprilTag::detect(), vpDetectorAprilTag::detect(), vpDetectorDataMatrixCode::detect(), vpDetectorFace::detect(), vpDetectorQRCode::detect(), getMessage(), getMessage(), vpDetectorBase(), and vpDetectorBase().

◆ m_nb_objects

size_t vpDetectorBase::m_nb_objects

protectedinherited

Number of detected objects.

Definition at line 130 of file vpDetectorBase.h.

Referenced by vpDetectorAprilTag::detect(), vpDetectorAprilTag::detect(), vpDetectorDataMatrixCode::detect(), vpDetectorFace::detect(), vpDetectorQRCode::detect(), getNbObjects(), vpDetectorBase(), and vpDetectorBase().

◆ m_polygon

std::vector<std::vector<vpImagePoint> > vpDetectorBase::m_polygon

protectedinherited

For each object, defines the polygon that contains the object.

Definition at line 128 of file vpDetectorBase.h.

Referenced by vpDetectorAprilTag::detect(), vpDetectorAprilTag::detect(), vpDetectorDataMatrixCode::detect(), vpDetectorFace::detect(), vpDetectorQRCode::detect(), getBBox(), getCog(), getMessage(), getPolygon(), getPolygon(), vpDetectorAprilTag::getTagsCorners(), vpDetectorBase(), and vpDetectorBase().

◆ m_poseEstimationMethod

vpPoseEstimationMethod vpDetectorAprilTag::m_poseEstimationMethod

protected

Definition at line 445 of file vpDetectorAprilTag.h.

Referenced by getPoseEstimationMethod(), setAprilTagFamily(), setAprilTagPoseEstimationMethod(), vpDetectorAprilTag(), and vpDetectorAprilTag().

◆ m_tagFamily

vpAprilTagFamily vpDetectorAprilTag::m_tagFamily

protected

Definition at line 446 of file vpDetectorAprilTag.h.

Referenced by vpDetectorAprilTag(), and vpDetectorAprilTag().

◆ m_timeout_ms

unsigned long vpDetectorBase::m_timeout_ms

protectedinherited

Detection timeout.

Definition at line 131 of file vpDetectorBase.h.

Referenced by vpDetectorDataMatrixCode::detect(), setTimeout(), vpDetectorBase(), and vpDetectorBase().

Public Types

Public Member Functions

Friends

Deprecated functions

Inherited functionalities from vpDetectorBase

Detailed Description

Tutorials & Examples

Member Enumeration Documentation

◆ vpAprilTagFamily

◆ vpPoseEstimationMethod

Constructor & Destructor Documentation

◆ vpDetectorAprilTag() [1/2]

◆ vpDetectorAprilTag() [2/2]

◆ ~vpDetectorAprilTag()

Member Function Documentation

◆ detect() [1/2]

◆ detect() [2/2]

◆ displayFrames() [1/2]

◆ displayFrames() [2/2]

◆ displayTags() [1/2]

◆ displayTags() [2/2]

◆ getAprilTagDecisionMarginThreshold()

◆ getAprilTagHammingDistanceThreshold()

◆ getBBox()

◆ getCog()

◆ getMessage() [1/2]

◆ getMessage() [2/2]

◆ getNbObjects()

◆ getPolygon() [1/2]

◆ getPolygon() [2/2]

◆ getPose()

◆ getPoseEstimationMethod()

◆ getTagImage()

◆ getTagsCorners()

◆ getTagsDecisionMargin()

◆ getTagsHammingDistance()

◆ getTagsId()

◆ getTagsPoints3D()

◆ isZAlignedWithCameraAxis()

◆ operator=()

◆ setAprilTagDebugOption()

◆ setAprilTagDecisionMarginThreshold()

◆ setAprilTagDecodeSharpening()

◆ setAprilTagFamily()

◆ setAprilTagHammingDistanceThreshold()

◆ setAprilTagNbThreads()

◆ setAprilTagPoseEstimationMethod()

◆ setAprilTagQuadDecimate()

◆ setAprilTagQuadSigma()

◆ setAprilTagRefineDecode()

◆ setAprilTagRefineEdges()

◆ setAprilTagRefinePose()

◆ setDisplayTag()

◆ setTimeout()

◆ setZAlignedWithCameraAxis()

Friends And Related Symbol Documentation

◆ swap

Member Data Documentation

◆ m_displayTag

◆ m_displayTagColor

◆ m_displayTagThickness

◆ m_message

◆ m_nb_objects

◆ m_polygon

◆ m_poseEstimationMethod

◆ m_tagFamily

◆ m_timeout_ms