手机摄像头校准-opencv答案

【问题标题】：phone camera calibration-opencv手机摄像头校准-opencv
【发布时间】：2020-01-27 23:55:00
【问题描述】：

我正在尝试使用 OpenCV 中提供的教程和棋盘图片来校准我的手机摄像头，但代码没有显示最终结果，我一直遇到这个错误：

NameError                                 Traceback (most recent call last)
<ipython-input-16-9dc3cfc36f25> in <module>
     33 
     34 cv2.destroyAllWindows()
---> 35 ret, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, gray.shape[::-1],None,None)

NameError: name 'gray' is not defined

这是我运行的代码

import numpy as np
import cv2
import glob
# termination criteria
criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 0.001)

# prepare object points, like (0,0,0), (1,0,0), (2,0,0) ....,(6,5,0)
objp = np.zeros((6*9,3), np.float64)
objp[:,:2] = np.mgrid[0:9,0:6].T.reshape(-1,2)

# Arrays to store object points and image points from all the images.
objpoints = [] # 3d point in real world space
imgpoints = [] # 2d points in image plane.

images = glob.glob('*/Users/ASUS/Desktop/Homework/Homework_1/im.jpg')

for fname in images:
    img = cv2.imread(fname)
    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

    # Find the chess board corners
    ret, corners = cv2.findChessboardCorners(gray, (9,6),None)
    print(ret)

    # If found, add object points, image points (after refining them)
    if ret == True:
        objpoints.append(objp)

        corners2 = cv2.cornerSubPix(gray,corners,(11,11),(-1,-1),criteria)
        imgpoints.append(corners2)

        # Draw and display the corners
        img = cv2.drawChessboardCorners(img, (9,6), corners2,ret)
        cv2.imshow('img',img)
        cv2.waitKey(500)

cv2.destroyAllWindows()
ret, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, gray.shape[::-1],None,None)

【问题讨论】：

它说“'灰色'未定义”。在 calibrateCamera 之前检查灰度图像，看看它是否是有效的图像。

标签： python opencv camera-calibration

【解决方案1】：

您在 for 循环中加载图像，gray 仅在此处定义。然后在最后一行的循环之外引用它以获取图像尺寸，但 gray 超出范围。

在 for 循环之前创建一个保存图像尺寸的变量并将其填充到循环中应该可以解决问题。

dims = None

for fname in images:
    img = cv2.imread(fname)
    dims = img.shape[::-1]

(...)

ret, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, dims, None, None)

【讨论】：