vis_tools.py 文件源码

def find_black_center(cv_img, msk):

    """
    Given an opencv image containing a dark object on a light background
    and a mask of objects to ignore (a gripper, for instance),
    return the coordinates of the centroid of the largest object
    (excluding those touching edges) and its simplified contour.
    If none detected or problem with centroid, return [(-1, -1), False].
    """

    # Convert to black and white
    (rows, cols, _) = cv_img.shape
    grey_img = cv2.cvtColor(cv_img, cv2.COLOR_BGR2GRAY)
    grey_img = cv2.bilateralFilter(grey_img, 11, 17, 17)
    _, outlines = cv2.threshold(
        grey_img, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)

    # Subtract gripper
    msk_out = cv2.subtract(cv2.bitwise_not(outlines), msk)

    # Remove objects touching edges
    flood_fill_edges(msk_out, 30)

    # Find contours
    _, contours, _ = cv2.findContours(
        msk_out, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

    if len(contours) == 0:
        return [(-1, -1), False]

    # Find largest contour
    max_area = 0
    for cnt in contours:
        area = cv2.contourArea(cnt)
        if area > max_area:
            contour = cnt
            max_area = area

    # Approximate contour
    epsilon = 0.025 * cv2.arcLength(contour, True)
    approx = cv2.approxPolyDP(contour, epsilon, True)

    # Find centroid
    try:
        M = cv2.moments(approx)
        cx = int(M['m10']/M['m00'])
        cy = int(M['m01']/M['m00'])
        return [(cx, cy), approx]
    except ZeroDivisionError:
        return [(-1, -1), False]