Spot Robot Calibration Board Boston Bynamics e OpenCV

Ho avuto la fortuna di poter usare una enorma Charuco Board legata al cane robot Spot della Boston Dynamics

Nonostante non sia esplicitamente indicato si tratta di una Charuco Board 4x4_100 di 9 colonne e 4 righe

Per usarla per calibrare una camera si puo' usare il seguente script OpenCV

Attenzione: per funzionare lo script necessita setLegacyPattern(True)

import os
import numpy as np
import cv2

# ------------------------------
# ENTER YOUR REQUIREMENTS HERE:
ARUCO_DICT = cv2.aruco.DICT_4X4_250
SQUARES_VERTICALLY = 9
SQUARES_HORIZONTALLY = 4
SQUARE_LENGTH = 0.115
MARKER_LENGTH = 0.09
# ...
PATH_TO_YOUR_IMAGES = './hikvision'
# ------------------------------

def calibrate_and_save_parameters():
    # Define the aruco dictionary and charuco board
    dictionary = cv2.aruco.getPredefinedDictionary(ARUCO_DICT)
    board = cv2.aruco.CharucoBoard((SQUARES_VERTICALLY, SQUARES_HORIZONTALLY), SQUARE_LENGTH, MARKER_LENGTH, dictionary)
    board.setLegacyPattern(True)
    params = cv2.aruco.DetectorParameters()
    params.cornerRefinementMethod = 0


    image_files = [os.path.join(PATH_TO_YOUR_IMAGES, f) for f in os.listdir(PATH_TO_YOUR_IMAGES) if f.endswith(".jpg")]
    image_files.sort()

    all_charuco_corners = []
    all_charuco_ids = []

    for image_file in image_files:
        print(image_file)
        image = cv2.imread(image_file)
        marker_corners, marker_ids, _ = cv2.aruco.detectMarkers(image, dictionary, parameters=params)

        # If at least one marker is detected
        if len(marker_ids) > 0:
            charuco_retval, charuco_corners, charuco_ids = cv2.aruco.interpolateCornersCharuco(marker_corners, marker_ids, image, board)

            if charuco_retval:
                all_charuco_corners.append(charuco_corners)
                all_charuco_ids.append(charuco_ids)

    # Calibrate camera
    retval, camera_matrix, dist_coeffs, rvecs, tvecs = cv2.aruco.calibrateCameraCharuco(all_charuco_corners, all_charuco_ids, board, image.shape[:2], None, None)

    # Save calibration data
    np.save('hik_camera_matrix.npy', camera_matrix)
    np.save('hik_dist_coeffs.npy', dist_coeffs)


    cv2.destroyAllWindows()

calibrate_and_save_parameters()