opencv--opencv/samples/cpp/tutorial_code/objectDetection/calibrate_camera_charuco.cpp

#include <iostream>
#include <vector>
#include <opencv2/calib3d.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/objdetect/charuco_detector.hpp>
#include "aruco_samples_utility.hpp"

using namespace std;
using namespace cv;

namespace {
const char* about =
        "Calibration using a ChArUco board\n"
        "  To capture a frame for calibration, press 'c',\n"
        "  If input comes from video, press any key for next frame\n"
        "  To finish capturing, press 'ESC' key and calibration starts.\n";
const char* keys  =
        "{w        |       | Number of squares in X direction }"
        "{h        |       | Number of squares in Y direction }"
        "{sl       |       | Square side length (in meters) }"
        "{ml       |       | Marker side length (in meters) }"
        "{d        |       | dictionary: DICT_4X4_50=0, DICT_4X4_100=1, DICT_4X4_250=2,"
        "DICT_4X4_1000=3, DICT_5X5_50=4, DICT_5X5_100=5, DICT_5X5_250=6, DICT_5X5_1000=7, "
        "DICT_6X6_50=8, DICT_6X6_100=9, DICT_6X6_250=10, DICT_6X6_1000=11, DICT_7X7_50=12,"
        "DICT_7X7_100=13, DICT_7X7_250=14, DICT_7X7_1000=15, DICT_ARUCO_ORIGINAL=16,"
        "DICT_APRILTAG_16h5=17, DICT_APRILTAG_25h9=18, DICT_APRILTAG_36h10=19, DICT_APRILTAG_36h11=20, DICT_ARUCO_MIP_36h12=21}"
        "{cd       |       | Input file with custom dictionary }"
        "{@outfile |cam.yml| Output file with calibrated camera parameters }"
        "{v        |       | Input from video file, if ommited, input comes from camera }"
        "{ci       | 0     | Camera id if input doesnt come from video (-v) }"
        "{dp       |       | File of marker detector parameters }"
        "{rs       | false | Apply refind strategy }"
        "{zt       | false | Assume zero tangential distortion }"
        "{a        |       | Fix aspect ratio (fx/fy) to this value }"
        "{pc       | false | Fix the principal point at the center }"
        "{sc       | false | Show detected chessboard corners after calibration }";
}


int main(int argc, char *argv[]) {
    CommandLineParser parser(argc, argv, keys);
    parser.about(about);

    if(argc < 7) {
        parser.printMessage();
        return 0;
    }

    int squaresX = parser.get<int>("w");
    int squaresY = parser.get<int>("h");
    float squareLength = parser.get<float>("sl");
    float markerLength = parser.get<float>("ml");
    string outputFile = parser.get<string>(0);

    bool showChessboardCorners = parser.get<bool>("sc");

    int calibrationFlags = 0;
    float aspectRatio = 1;
    if(parser.has("a")) {
        calibrationFlags |= CALIB_FIX_ASPECT_RATIO;
        aspectRatio = parser.get<float>("a");
    }
    if(parser.get<bool>("zt")) calibrationFlags |= CALIB_ZERO_TANGENT_DIST;
    if(parser.get<bool>("pc")) calibrationFlags |= CALIB_FIX_PRINCIPAL_POINT;

    aruco::DetectorParameters detectorParams = readDetectorParamsFromCommandLine(parser);
    aruco::Dictionary dictionary = readDictionatyFromCommandLine(parser);

    bool refindStrategy = parser.get<bool>("rs");
    int camId = parser.get<int>("ci");
    String video;

    if(parser.has("v")) {
        video = parser.get<String>("v");
    }

    if(!parser.check()) {
        parser.printErrors();
        return 0;
    }

    VideoCapture inputVideo;
    int waitTime;
    if(!video.empty()) {
        inputVideo.open(video);
        waitTime = 0;
    } else {
        inputVideo.open(camId);
        waitTime = 10;
    }

    aruco::CharucoParameters charucoParams;
    if(refindStrategy) {
        charucoParams.tryRefineMarkers = true;
    }

    //! [CalibrationWithCharucoBoard1]
    // Create charuco board object and CharucoDetector
    aruco::CharucoBoard board(Size(squaresX, squaresY), squareLength, markerLength, dictionary);
    aruco::CharucoDetector detector(board, charucoParams, detectorParams);

    // Collect data from each frame
    vector<Mat> allCharucoCorners, allCharucoIds;

    vector<vector<Point2f>> allImagePoints;
    vector<vector<Point3f>> allObjectPoints;

    vector<Mat> allImages;
    Size imageSize;

    while(inputVideo.grab()) {
        Mat image, imageCopy;
        inputVideo.retrieve(image);

        vector<int> markerIds;
        vector<vector<Point2f>> markerCorners;
        Mat currentCharucoCorners, currentCharucoIds;
        vector<Point3f> currentObjectPoints;
        vector<Point2f> currentImagePoints;

        // Detect ChArUco board
        detector.detectBoard(image, currentCharucoCorners, currentCharucoIds);
        //! [CalibrationWithCharucoBoard1]

        // Draw results
        image.copyTo(imageCopy);
        if(!markerIds.empty()) {
            aruco::drawDetectedMarkers(imageCopy, markerCorners);
        }

        if(currentCharucoCorners.total() > 3) {
            aruco::drawDetectedCornersCharuco(imageCopy, currentCharucoCorners, currentCharucoIds);
        }

        putText(imageCopy, "Press 'c' to add current frame. 'ESC' to finish and calibrate",
                Point(10, 20), FONT_HERSHEY_SIMPLEX, 0.5, Scalar(255, 0, 0), 2);

        imshow("out", imageCopy);

        // Wait for key pressed
        char key = (char)waitKey(waitTime);

        if(key == 27) {
            break;
        }

        //! [CalibrationWithCharucoBoard2]
        if(key == 'c' && currentCharucoCorners.total() > 3) {
            // Match image points
            board.matchImagePoints(currentCharucoCorners, currentCharucoIds, currentObjectPoints, currentImagePoints);

            if(currentImagePoints.empty() || currentObjectPoints.empty()) {
                cout << "Point matching failed, try again." << endl;
                continue;
            }

            cout << "Frame captured" << endl;

            allCharucoCorners.push_back(currentCharucoCorners);
            allCharucoIds.push_back(currentCharucoIds);
            allImagePoints.push_back(currentImagePoints);
            allObjectPoints.push_back(currentObjectPoints);
            allImages.push_back(image);

            imageSize = image.size();
        }
    }
    //! [CalibrationWithCharucoBoard2]

    if(allCharucoCorners.size() < 4) {
        cerr << "Not enough corners for calibration" << endl;
        return 0;
    }

    //! [CalibrationWithCharucoBoard3]
    Mat cameraMatrix, distCoeffs;

    if(calibrationFlags & CALIB_FIX_ASPECT_RATIO) {
        cameraMatrix = Mat::eye(3, 3, CV_64F);
        cameraMatrix.at<double>(0, 0) = aspectRatio;
    }

    // Calibrate camera using ChArUco
    double repError = calibrateCamera(allObjectPoints, allImagePoints, imageSize, cameraMatrix, distCoeffs,
                                      noArray(), noArray(), noArray(), noArray(), noArray(), calibrationFlags);
    //! [CalibrationWithCharucoBoard3]

    bool saveOk =  saveCameraParams(outputFile, imageSize, aspectRatio, calibrationFlags,
                                    cameraMatrix, distCoeffs, repError);

    if(!saveOk) {
        cerr << "Cannot save output file" << endl;
        return 0;
    }

    cout << "Rep Error: " << repError << endl;
    cout << "Calibration saved to " << outputFile << endl;

    // Show interpolated charuco corners for debugging
    if(showChessboardCorners) {
        for(size_t frame = 0; frame < allImages.size(); frame++) {
            Mat imageCopy = allImages[frame].clone();

            if(allCharucoCorners[frame].total() > 0) {
                aruco::drawDetectedCornersCharuco(imageCopy, allCharucoCorners[frame], allCharucoIds[frame]);
            }

            imshow("out", imageCopy);
            char key = (char)waitKey(0);
            if(key == 27) {
                break;
            }
        }
    }
    return 0;
}