tagdetectutils Namespace Reference

Namespace containing function to assist in tag detection. More...

Classes
struct	ArucoTag
	Represents a single ArUco tag. Combines attributes from TorchTag, TensorflowTag, and the original ArucoTag structs. More...

Enumerations
enum class	TagDetectionMethod { eUnknown , eOpenCV , eTorch , eTensorflow }
	Enum class to define the different tag detection methods available. More...

Functions
cv::Point2f	FindTagCenter (const ArucoTag &stTag)
	Given an tagdetectutils::ArucoTag struct find the center point of the corners.
void	EstimatePoseFromPNP (cv::Mat &cvCameraMatrix, cv::Mat &cvDistCoeffs, ArucoTag &stTag)
	Estimate the pose of a position with respect to the observer using an image.
void	EstimatePoseFromCameraFrame (ArucoTag &stTag)
	Estimate the pose of a tag from a camera frame.

Detailed Description

Namespace containing function to assist in tag detection.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-05-05

Enumeration Type Documentation

TagDetectionMethod

enum class tagdetectutils::TagDetectionMethod

strong

Enum class to define the different tag detection methods available.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-04-03

    {
        eUnknown,      // Unknown detection method.
        eOpenCV,       // Standard OpenCV detection using the ArUco library.
        eTorch,        // Torch detection using a YOLO model.
        eTensorflow    // Tensorflow detection using a YOLO model.
    };

Function Documentation

FindTagCenter()

cv::Point2f tagdetectutils::FindTagCenter ( const ArucoTag &  stTag )

inline

Given an tagdetectutils::ArucoTag struct find the center point of the corners.

Parameters

stTag

- The tag to find the center of.

Returns

cv::Point2f - The resultant center point within the image.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-02-13

    {
        // Calculate the center point of the tag.
        cv::Point2f cvCenter = cv::Point2f(stTag.pBoundingBox->x + stTag.pBoundingBox->width / 2, stTag.pBoundingBox->y + stTag.pBoundingBox->height / 2);
 
        return cvCenter;
    }

EstimatePoseFromPNP()

void tagdetectutils::EstimatePoseFromPNP ( cv::Mat &  cvCameraMatrix, cv::Mat &  cvDistCoeffs, ArucoTag &  stTag  )

inline

Estimate the pose of a position with respect to the observer using an image.

Parameters

cvCameraMatrix	- Matrix of camera's parameters including focal length and optical center.
cvDistCoeffs	- Matrix of the camera's distortion coefficients.
stTag	- The tag we are estimating the pose of and then storing the distance and angle calculations in.

Author

jspencerpittman (jspen.nosp@m.cerp.nosp@m.ittma.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2023-10-06

    {
        // rotVec is how the tag is orientated with respect to the camera. It's 3 numbers defining an axis of rotation around which we rotate the angle which is the
        // euclidean distance of the vector. transVec is the XYZ translation of the tag from the camera if you image the convergence of light as a pinhole sitting at
        // (0,0,0) in space.
        cv::Vec3d cvRotVec, cvTransVec;
 
        // Set expected object coordinate system shape.
        cv::Mat cvObjPoints(4, 1, CV_32FC3);
        cvObjPoints.at<cv::Vec3f>(0) = cv::Vec3f{0, 0, 0};                                                                  // Top-left corner.
        cvObjPoints.at<cv::Vec3f>(1) = cv::Vec3f{constants::ARUCO_TAG_SIDE_LENGTH, 0, 0};                                   // Bottom-left corner.
        cvObjPoints.at<cv::Vec3f>(2) = cv::Vec3f{0, constants::ARUCO_TAG_SIDE_LENGTH, 0};                                   // Top-right corner.
        cvObjPoints.at<cv::Vec3f>(3) = cv::Vec3f{constants::ARUCO_TAG_SIDE_LENGTH, constants::ARUCO_TAG_SIDE_LENGTH, 0};    // Bottom-right corner.
 
        // Repackage tag image points into a mat.
        cv::Mat cvImgPoints(4, 1, CV_32FC3);
        cvImgPoints.at<cv::Vec3f>(0) = cv::Vec3f{static_cast<float>(stTag.pBoundingBox->x), static_cast<float>(stTag.pBoundingBox->y), 0.0f};      // Top-left corner.
        cvImgPoints.at<cv::Vec3f>(1) =
            cv::Vec3f{static_cast<float>(stTag.pBoundingBox->x), static_cast<float>(stTag.pBoundingBox->y + stTag.pBoundingBox->height), 0.0f};    // Bottom-left corner.
        cvImgPoints.at<cv::Vec3f>(2) =
            cv::Vec3f{static_cast<float>(stTag.pBoundingBox->x + stTag.pBoundingBox->width), static_cast<float>(stTag.pBoundingBox->y), 0.0f};     // Top-right corner.
        cvImgPoints.at<cv::Vec3f>(3) = cv::Vec3f{static_cast<float>(stTag.pBoundingBox->x + stTag.pBoundingBox->width),
                                                 static_cast<float>(stTag.pBoundingBox->y + stTag.pBoundingBox->height),
                                                 0.0f};    // Bottom-right corner.
 
        // Use solve perspective n' point algorithm to estimate pose of the tag.
        cv::solvePnP(cvObjPoints, cvImgPoints, cvCameraMatrix, cvDistCoeffs, cvRotVec, cvTransVec);
 
        // Grab (x,y,z) coordinates from where the tag was detected
        double dForward = cvTransVec[2];
        double dRight   = cvTransVec[0];
        double dUp      = cvTransVec[1];
 
        // Calculate euclidean distance from ZED camera left eye to the point of interest
        stTag.dStraightLineDistance = std::sqrt(std::pow(dForward, 2) + std::pow(dRight, 2) + std::pow(dUp, 2));
 
        // Calculate the angle on plane horizontal to the viewpoint
        stTag.dYawAngle = std::atan2(dRight, dForward);
    }

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EstimatePoseFromCameraFrame()

void tagdetectutils::EstimatePoseFromCameraFrame ( ArucoTag &  stTag )

inline

• Estimate the pose of a tag from a camera frame.

Parameters

stTag

- The tag to estimate the pose of.

Note

In order for this to be accurate, the camera's horizontal field of view (HFOV) and the camera frame size must be known.

Author

sam_hajdukiewicz (saman.nosp@m.thah.nosp@m.ajduk.nosp@m.iewi.nosp@m.cz@gm.nosp@m.ail..nosp@m.com) :3

Date

2025-04-04

    {
        // Use camera field of view and camera frame size to determine tag angle in degrees from center of camera.
        double dDegreesPerPixel = stTag.dHorizontalFOV / stTag.cvImageResolution.width;
        // Find tag error in pixels from center of image.
        double dTagErrorX = (stTag.pBoundingBox->x + stTag.pBoundingBox->width / 2) - (stTag.cvImageResolution.width / 2);
        // Find angle error.
        double dTagAngleX = dTagErrorX * dDegreesPerPixel;
        // Reassign yaw and distance to tag.
        stTag.dYawAngle = dTagAngleX;
 
        // For the distance, we'll just use the screen percentage of the tag.
        stTag.dStraightLineDistance = (stTag.pBoundingBox->area() / (stTag.cvImageResolution.width * stTag.cvImageResolution.height)) * 100.0;
    }

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