// This file is part of OpenCV project. // It is subject to the license terms in the LICENSE file found in the top-level directory // of this distribution and at http://opencv.org/license.html #ifndef OPENCV_OBJDETECT_ARUCO_DETECTOR_HPP #define OPENCV_OBJDETECT_ARUCO_DETECTOR_HPP #include #include namespace cv { namespace aruco { //! @addtogroup objdetect_aruco //! @{ enum CornerRefineMethod{ CORNER_REFINE_NONE, ///< Tag and corners detection based on the ArUco approach CORNER_REFINE_SUBPIX, ///< ArUco approach and refine the corners locations using corner subpixel accuracy CORNER_REFINE_CONTOUR, ///< ArUco approach and refine the corners locations using the contour-points line fitting CORNER_REFINE_APRILTAG, ///< Tag and corners detection based on the AprilTag 2 approach @cite wang2016iros }; /** @brief struct DetectorParameters is used by ArucoDetector */ struct CV_EXPORTS_W_SIMPLE DetectorParameters { CV_WRAP DetectorParameters() { adaptiveThreshWinSizeMin = 3; adaptiveThreshWinSizeMax = 23; adaptiveThreshWinSizeStep = 10; adaptiveThreshConstant = 7; minMarkerPerimeterRate = 0.03; maxMarkerPerimeterRate = 4.; polygonalApproxAccuracyRate = 0.03; minCornerDistanceRate = 0.05; minDistanceToBorder = 3; minMarkerDistanceRate = 0.125; cornerRefinementMethod = (int)CORNER_REFINE_NONE; cornerRefinementWinSize = 5; relativeCornerRefinmentWinSize = 0.3f; cornerRefinementMaxIterations = 30; cornerRefinementMinAccuracy = 0.1; markerBorderBits = 1; perspectiveRemovePixelPerCell = 4; perspectiveRemoveIgnoredMarginPerCell = 0.13; maxErroneousBitsInBorderRate = 0.35; minOtsuStdDev = 5.0; errorCorrectionRate = 0.6; aprilTagQuadDecimate = 0.0; aprilTagQuadSigma = 0.0; aprilTagMinClusterPixels = 5; aprilTagMaxNmaxima = 10; aprilTagCriticalRad = (float)(10* CV_PI /180); aprilTagMaxLineFitMse = 10.0; aprilTagMinWhiteBlackDiff = 5; aprilTagDeglitch = 0; detectInvertedMarker = false; useAruco3Detection = false; minSideLengthCanonicalImg = 32; minMarkerLengthRatioOriginalImg = 0.0; } /** @brief Read a new set of DetectorParameters from FileNode (use FileStorage.root()). */ CV_WRAP bool readDetectorParameters(const FileNode& fn); /** @brief Write a set of DetectorParameters to FileStorage */ CV_WRAP bool writeDetectorParameters(FileStorage& fs, const String& name = String()); /// minimum window size for adaptive thresholding before finding contours (default 3). CV_PROP_RW int adaptiveThreshWinSizeMin; /// maximum window size for adaptive thresholding before finding contours (default 23). CV_PROP_RW int adaptiveThreshWinSizeMax; /// increments from adaptiveThreshWinSizeMin to adaptiveThreshWinSizeMax during the thresholding (default 10). CV_PROP_RW int adaptiveThreshWinSizeStep; /// constant for adaptive thresholding before finding contours (default 7) CV_PROP_RW double adaptiveThreshConstant; /** @brief determine minimum perimeter for marker contour to be detected. * * This is defined as a rate respect to the maximum dimension of the input image (default 0.03). */ CV_PROP_RW double minMarkerPerimeterRate; /** @brief determine maximum perimeter for marker contour to be detected. * * This is defined as a rate respect to the maximum dimension of the input image (default 4.0). */ CV_PROP_RW double maxMarkerPerimeterRate; /// minimum accuracy during the polygonal approximation process to determine which contours are squares. (default 0.03) CV_PROP_RW double polygonalApproxAccuracyRate; /// minimum distance between corners for detected markers relative to its perimeter (default 0.05) CV_PROP_RW double minCornerDistanceRate; /// minimum distance of any corner to the image border for detected markers (in pixels) (default 3) CV_PROP_RW int minDistanceToBorder; /** @brief minimum average distance between the corners of the two markers to be grouped (default 0.125). * * The rate is relative to the smaller perimeter of the two markers. * Two markers are grouped if average distance between the corners of the two markers is less than * min(MarkerPerimeter1, MarkerPerimeter2)*minMarkerDistanceRate. * * default value is 0.125 because 0.125*MarkerPerimeter = (MarkerPerimeter / 4) * 0.5 = half the side of the marker. * * @note default value was changed from 0.05 after 4.8.1 release, because the filtering algorithm has been changed. * Now a few candidates from the same group can be added to the list of candidates if they are far from each other. * @sa minGroupDistance. */ CV_PROP_RW double minMarkerDistanceRate; /** @brief minimum average distance between the corners of the two markers in group to add them to the list of candidates * * The average distance between the corners of the two markers is calculated relative to its module size (default 0.21). */ CV_PROP_RW float minGroupDistance = 0.21f; /** @brief default value CORNER_REFINE_NONE */ CV_PROP_RW int cornerRefinementMethod; /** @brief maximum window size for the corner refinement process (in pixels) (default 5). * * The window size may decrease if the ArUco marker is too small, check relativeCornerRefinmentWinSize. * The final window size is calculated as: * min(cornerRefinementWinSize, averageArucoModuleSize*relativeCornerRefinmentWinSize), * where averageArucoModuleSize is average module size of ArUco marker in pixels. * (ArUco marker is composed of black and white modules) */ CV_PROP_RW int cornerRefinementWinSize; /** @brief Dynamic window size for corner refinement relative to Aruco module size (default 0.3). * * The final window size is calculated as: * min(cornerRefinementWinSize, averageArucoModuleSize*relativeCornerRefinmentWinSize), * where averageArucoModuleSize is average module size of ArUco marker in pixels. * (ArUco marker is composed of black and white modules) * In the case of markers located far from each other, it may be useful to increase the value of the parameter to 0.4-0.5. * In the case of markers located close to each other, it may be useful to decrease the parameter value to 0.1-0.2. */ CV_PROP_RW float relativeCornerRefinmentWinSize; /// maximum number of iterations for stop criteria of the corner refinement process (default 30). CV_PROP_RW int cornerRefinementMaxIterations; /// minimum error for the stop cristeria of the corner refinement process (default: 0.1) CV_PROP_RW double cornerRefinementMinAccuracy; /// number of bits of the marker border, i.e. marker border width (default 1). CV_PROP_RW int markerBorderBits; /// number of bits (per dimension) for each cell of the marker when removing the perspective (default 4). CV_PROP_RW int perspectiveRemovePixelPerCell; /** @brief width of the margin of pixels on each cell not considered for the determination of the cell bit. * * Represents the rate respect to the total size of the cell, i.e. perspectiveRemovePixelPerCell (default 0.13) */ CV_PROP_RW double perspectiveRemoveIgnoredMarginPerCell; /** @brief maximum number of accepted erroneous bits in the border (i.e. number of allowed white bits in the border). * * Represented as a rate respect to the total number of bits per marker (default 0.35). */ CV_PROP_RW double maxErroneousBitsInBorderRate; /** @brief minimun standard deviation in pixels values during the decodification step to apply Otsu * thresholding (otherwise, all the bits are set to 0 or 1 depending on mean higher than 128 or not) (default 5.0) */ CV_PROP_RW double minOtsuStdDev; /// error correction rate respect to the maximun error correction capability for each dictionary (default 0.6). CV_PROP_RW double errorCorrectionRate; /** @brief April :: User-configurable parameters. * * 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 */ CV_PROP_RW float aprilTagQuadDecimate; /// what Gaussian blur should be applied to the segmented image (used for quad detection?) CV_PROP_RW float aprilTagQuadSigma; // April :: Internal variables /// reject quads containing too few pixels (default 5). CV_PROP_RW int aprilTagMinClusterPixels; /// how many corner candidates to consider when segmenting a group of pixels into a quad (default 10). CV_PROP_RW int aprilTagMaxNmaxima; /** @brief reject quads where pairs of edges have angles that are close to straight or close to 180 degrees. * * Zero means that no quads are rejected. (In radians) (default 10*PI/180) */ CV_PROP_RW float aprilTagCriticalRad; /// when fitting lines to the contours, what is the maximum mean squared error CV_PROP_RW float aprilTagMaxLineFitMse; /** @brief add an extra check that the white model must be (overall) brighter than the black model. * * When we build our model of black & white pixels, we add an extra check that the white model must be (overall) * brighter than the black model. How much brighter? (in pixel values, [0,255]), (default 5) */ CV_PROP_RW int aprilTagMinWhiteBlackDiff; /// should the thresholded image be deglitched? Only useful for very noisy images (default 0). CV_PROP_RW int aprilTagDeglitch; /** @brief to check if there is a white marker. * * In order to generate a "white" marker just invert a normal marker by using a tilde, ~markerImage. (default false) */ CV_PROP_RW bool detectInvertedMarker; /** @brief enable the new and faster Aruco detection strategy. * * Proposed in the paper: * Romero-Ramirez et al: Speeded up detection of squared fiducial markers (2018) * https://www.researchgate.net/publication/325787310_Speeded_Up_Detection_of_Squared_Fiducial_Markers */ CV_PROP_RW bool useAruco3Detection; /// minimum side length of a marker in the canonical image. Latter is the binarized image in which contours are searched. CV_PROP_RW int minSideLengthCanonicalImg; /// range [0,1], eq (2) from paper. The parameter tau_i has a direct influence on the processing speed. CV_PROP_RW float minMarkerLengthRatioOriginalImg; }; /** @brief struct RefineParameters is used by ArucoDetector */ struct CV_EXPORTS_W_SIMPLE RefineParameters { CV_WRAP RefineParameters(float minRepDistance = 10.f, float errorCorrectionRate = 3.f, bool checkAllOrders = true); /** @brief Read a new set of RefineParameters from FileNode (use FileStorage.root()). */ CV_WRAP bool readRefineParameters(const FileNode& fn); /** @brief Write a set of RefineParameters to FileStorage */ CV_WRAP bool writeRefineParameters(FileStorage& fs, const String& name = String()); /** @brief minRepDistance minimum distance between the corners of the rejected candidate and the reprojected marker in order to consider it as a correspondence. */ CV_PROP_RW float minRepDistance; /** @brief minRepDistance rate of allowed erroneous bits respect to the error correction capability of the used dictionary. * * -1 ignores the error correction step. */ CV_PROP_RW float errorCorrectionRate; /** @brief checkAllOrders consider the four posible corner orders in the rejectedCorners array. * * If it set to false, only the provided corner order is considered (default true). */ CV_PROP_RW bool checkAllOrders; }; /** @brief The main functionality of ArucoDetector class is detection of markers in an image with detectMarkers() method. * * After detecting some markers in the image, you can try to find undetected markers from this dictionary with * refineDetectedMarkers() method. * * @see DetectorParameters, RefineParameters */ class CV_EXPORTS_W ArucoDetector : public Algorithm { public: /** @brief Basic ArucoDetector constructor * * @param dictionary indicates the type of markers that will be searched * @param detectorParams marker detection parameters * @param refineParams marker refine detection parameters */ CV_WRAP ArucoDetector(const Dictionary &dictionary = getPredefinedDictionary(cv::aruco::DICT_4X4_50), const DetectorParameters &detectorParams = DetectorParameters(), const RefineParameters& refineParams = RefineParameters()); /** @brief Basic marker detection * * @param image input image * @param corners vector of detected marker corners. For each marker, its four corners * are provided, (e.g std::vector > ). For N detected markers, * the dimensions of this array is Nx4. The order of the corners is clockwise. * @param ids vector of identifiers of the detected markers. The identifier is of type int * (e.g. std::vector). For N detected markers, the size of ids is also N. * The identifiers have the same order than the markers in the imgPoints array. * @param rejectedImgPoints contains the imgPoints of those squares whose inner code has not a * correct codification. Useful for debugging purposes. * * Performs marker detection in the input image. Only markers included in the specific dictionary * are searched. For each detected marker, it returns the 2D position of its corner in the image * and its corresponding identifier. * Note that this function does not perform pose estimation. * @note The function does not correct lens distortion or takes it into account. It's recommended to undistort * input image with corresponding camera model, if camera parameters are known * @sa undistort, estimatePoseSingleMarkers, estimatePoseBoard */ CV_WRAP void detectMarkers(InputArray image, OutputArrayOfArrays corners, OutputArray ids, OutputArrayOfArrays rejectedImgPoints = noArray()) const; /** @brief Refine not detected markers based on the already detected and the board layout * * @param image input image * @param board layout of markers in the board. * @param detectedCorners vector of already detected marker corners. * @param detectedIds vector of already detected marker identifiers. * @param rejectedCorners vector of rejected candidates during the marker detection process. * @param cameraMatrix optional input 3x3 floating-point camera matrix * \f$A = \vecthreethree{f_x}{0}{c_x}{0}{f_y}{c_y}{0}{0}{1}\f$ * @param distCoeffs optional vector of distortion coefficients * \f$(k_1, k_2, p_1, p_2[, k_3[, k_4, k_5, k_6],[s_1, s_2, s_3, s_4]])\f$ of 4, 5, 8 or 12 elements * @param recoveredIdxs Optional array to returns the indexes of the recovered candidates in the * original rejectedCorners array. * * This function tries to find markers that were not detected in the basic detecMarkers function. * First, based on the current detected marker and the board layout, the function interpolates * the position of the missing markers. Then it tries to find correspondence between the reprojected * markers and the rejected candidates based on the minRepDistance and errorCorrectionRate parameters. * If camera parameters and distortion coefficients are provided, missing markers are reprojected * using projectPoint function. If not, missing marker projections are interpolated using global * homography, and all the marker corners in the board must have the same Z coordinate. */ CV_WRAP void refineDetectedMarkers(InputArray image, const Board &board, InputOutputArrayOfArrays detectedCorners, InputOutputArray detectedIds, InputOutputArrayOfArrays rejectedCorners, InputArray cameraMatrix = noArray(), InputArray distCoeffs = noArray(), OutputArray recoveredIdxs = noArray()) const; CV_WRAP const Dictionary& getDictionary() const; CV_WRAP void setDictionary(const Dictionary& dictionary); CV_WRAP const DetectorParameters& getDetectorParameters() const; CV_WRAP void setDetectorParameters(const DetectorParameters& detectorParameters); CV_WRAP const RefineParameters& getRefineParameters() const; CV_WRAP void setRefineParameters(const RefineParameters& refineParameters); /** @brief Stores algorithm parameters in a file storage */ virtual void write(FileStorage& fs) const override; /** @brief simplified API for language bindings */ CV_WRAP inline void write(FileStorage& fs, const String& name) { Algorithm::write(fs, name); } /** @brief Reads algorithm parameters from a file storage */ CV_WRAP virtual void read(const FileNode& fn) override; protected: struct ArucoDetectorImpl; Ptr arucoDetectorImpl; }; /** @brief Draw detected markers in image * * @param image input/output image. It must have 1 or 3 channels. The number of channels is not altered. * @param corners positions of marker corners on input image. * (e.g std::vector > ). For N detected markers, the dimensions of * this array should be Nx4. The order of the corners should be clockwise. * @param ids vector of identifiers for markers in markersCorners . * Optional, if not provided, ids are not painted. * @param borderColor color of marker borders. Rest of colors (text color and first corner color) * are calculated based on this one to improve visualization. * * Given an array of detected marker corners and its corresponding ids, this functions draws * the markers in the image. The marker borders are painted and the markers identifiers if provided. * Useful for debugging purposes. */ CV_EXPORTS_W void drawDetectedMarkers(InputOutputArray image, InputArrayOfArrays corners, InputArray ids = noArray(), Scalar borderColor = Scalar(0, 255, 0)); /** @brief Generate a canonical marker image * * @param dictionary dictionary of markers indicating the type of markers * @param id identifier of the marker that will be returned. It has to be a valid id in the specified dictionary. * @param sidePixels size of the image in pixels * @param img output image with the marker * @param borderBits width of the marker border. * * This function returns a marker image in its canonical form (i.e. ready to be printed) */ CV_EXPORTS_W void generateImageMarker(const Dictionary &dictionary, int id, int sidePixels, OutputArray img, int borderBits = 1); //! @} } } #endif