Question

我正按照这些说明尝试校准鱼眼镜头 here 在那里你可以找到我用于校准部分的完整代码。

我到达这一点：

N_OK = len(objpoints)
K = np.zeros((3, 3))
D = np.zeros((4, 1))
rvecs = [np.zeros((1, 1, 3), dtype=np.float64) for i in range(N_OK)]
tvecs = [np.zeros((1, 1, 3), dtype=np.float64) for i in range(N_OK)]  
rms, _, _, _, _ = \
    cv2.fisheye.calibrate(
        objpoints,
        imgpoints,
        gray.shape[::-1],
        K,
        D,
        rvecs,
        tvecs,
        calibration_flags,
        (cv2.TERM_CRITERIA_EPS+cv2.TERM_CRITERIA_MAX_ITER, 30, 1e-3)
    )
print("Found " + str(N_OK) + " valid images for calibration")
print("DIM=" + str(_img_shape[::-1]))
print("K=np.array(" + str(K.tolist()) + ")")
print("D=np.array(" + str(D.tolist()) + ")")

我收到此错误：

Traceback (most recent call last)
<ipython-input-10-deaca9981fe4> in <module>()
     13         tvecs,
     14         calibration_flags,
---> 15         (cv2.TERM_CRITERIA_EPS+cv2.TERM_CRITERIA_MAX_ITER, 30, 1e-3)
     16     )
     17 print("Found " + str(N_OK) + " valid images for calibration")

error: C:\ci\opencv_1512688052760\work\modules\calib3d\src\fisheye.cpp:1414: 
error: (-3) CALIB_CHECK_COND - Ill-conditioned matrix for input array 0 in 
function cv::internal::CalibrateExtrinsics

我不明白发生了什么，我只能在互联网上找到这么少的信息，有没有人经历过类似的事情，知道如何解决这个问题？

由于

这些是我使用的棋盘图片：

Answer 1

我认为这是因为你的变量calibration_flags设置为CALIB_CHECK_COND。尝试禁用此标志。如果没有它，我就可以不对你的图像进行破坏（见下面的链接）。

我不确定这项检查的用途（documentation不是很明确）。这个标志拒绝了我的gopro英雄3的一些图像¹，即使棋盘可见并被检测到。在我的情况下，20个中的一个图像没有通过此测试。该图像的棋盘靠近左边界。

在OpenCV版本中

¹＆gt; = 3.4.1 error message告诉你哪个图像没有通过测试

Answer 2

我没有在python中找到代码，所以我手动检查了棋盘边缘上的图像，并将它们逐个删除，直到错误消失。

Answer 3

正如@Ahmadiah所述，当棋盘格落在图像边缘附近时，可能会发生“病态”情况。解决此问题的一种方法是一张一张地删除图像，然后在导致校准失败的情况下重试。这是我们执行此操作的示例：

def calibrate_fisheye(all_image_points, all_true_points, image_size):
    """ Calibrate a fisheye camera from matching points.
    :param all_image_points: Sequence[Array(N, 2)[float32]] of (x, y) image coordinates of the points.  (see  cv2.findChessboardCorners)
    :param all_true_points: Sequence[Array(N, 3)[float32]] of (x,y,z) points.  (If from a grid, just put (x,y) on a regular grid and z=0)
        Note that each of these sets of points can be in its own reference frame,
    :param image_size: The (size_y, size_x) of the image.
    :return: (rms, mtx, dist, rvecs, tvecs) where
        rms: float - The root-mean-squared error
        mtx: array[3x3] A 3x3 camera intrinsics matrix
        dst: array[4x1] A (4x1) array of distortion coefficients
        rvecs: Sequence[array[N,3,1]] of estimated rotation vectors for each set of true points
        tvecs: Sequence[array[N,3,1]] of estimated translation vectors for each set of true points
    """
    assert len(all_true_points) == len(all_image_points)
    all_true_points = list(all_true_points)  # Because we'll modify it in place
    all_image_points = list(all_image_points)
    while True:
        assert len(all_true_points) > 0, "There are no valid images from which to calibrate."
        try:
            rms, mtx, dist, rvecs, tvecs = cv2.fisheye.calibrate(
                objectPoints=[p[None, :, :] for p in all_true_points],
                imagePoints=[p[:, None, :] for p in all_image_points],
                image_size=image_size,
                K=np.zeros((3, 3)),
                D=np.zeros((4, 1)),
                flags=cv2.fisheye.CALIB_RECOMPUTE_EXTRINSIC + cv2.fisheye.CALIB_CHECK_COND + cv2.fisheye.CALIB_FIX_SKEW,
                criteria=(cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 1e-6),
            )
            print('Found a calibration based on {} well-conditioned images.'.format(len(all_true_points)))
            return rms, mtx, dist, rvecs, tvecs
        except cv2.error as err:
            try:
                idx = int(err.message.split('array ')[1][0])  # Parse index of invalid image from error message
                all_true_points.pop(idx)
                all_image_points.pop(idx)
                print("Removed ill-conditioned image {} from the data.  Trying again...".format(idx))
            except IndexError:
                raise err

Answer 4

我的opencv版本是4.0+，我用这个方法sloves它

rms, _, _, _, _ = \
cv2.fisheye.calibrate(
    objpoints,
    imgpoints,
    #gray.shape[::-1],
    gray.shape,
    K,
    D,
    rvecs,
    tvecs,
    calibration_flags,
    (cv2.TERM_CRITERIA_EPS+cv2.TERM_CRITERIA_MAX_ITER, 30, 1e-3)
)

OpenCV - 校准鱼眼镜头错误（病态矩阵）

4 个答案: