title: Python 2.7: Error in cv2.stereoCalibrate(). Required argument 'distCoeffs1' (pos 5) not found
body: <p>I was doing stereo camera calibration using Python 2.7 and OpenCV 3.3. The code I used is (I got it from <em><a href="https://stackoverflow.com/questions/28222763/stereo-calibration-opencv-python-and-disparity-map">Stereo Calibration Opencv Python and Disparity Map</a></em>):</p>
  <pre><code>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*7,3), np.float32)
  objp[:,:2] = np.mgrid[0:7,0:6].T.reshape(-1,2)
  
  # Arrays to store object points and image points from all the images.
  objpointsL = [] # 3d point in real world space
  imgpointsL = [] # 2d points in image plane.
  objpointsR = []
  imgpointsR = []
  
  images = glob.glob('left*.jpg')
  
  for fname in images:
      img = cv2.imread(fname)
      grayL = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
  
      # Find the chess board corners
      ret, cornersL = cv2.findChessboardCorners(grayL, (7,6),None)
      # If found, add object points, image points (after refining them)
      if ret == True:
          objpointsL.append(objp)
  
          cv2.cornerSubPix(grayL,cornersL,(11,11),(-1,-1),criteria)
          imgpointsL.append(cornersL)
  
  images = glob.glob('right*.jpg')
  
  for fname in images:
      img = cv2.imread(fname)
      grayR = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
  
      # Find the chess board corners
      ret, cornersR = cv2.findChessboardCorners(grayR, (7,6),None)
  
      # If found, add object points, image points (after refining them)
      if ret == True:
          objpointsR.append(objp)
  
          cv2.cornerSubPix(grayR,cornersR,(11,11),(-1,-1),criteria)
          imgpointsR.append(cornersR)
  
  
  retval,cameraMatrix1, distCoeffs1, cameraMatrix2, distCoeffs2, R, T, E, F = cv2.stereoCalibrate(objpointsL, imgpointsL, imgpointsR, (640,480))
  </code></pre>
  <p>But I got error like:</p>
  <pre><code>retval,cameraMatrix1, distCoeffs1, cameraMatrix2, distCoeffs2, R, T, E, F = cv2.stereoCalibrate(objpointsL, imgpointsL, imgpointsR, (640,480))
  TypeError: Required argument 'distCoeffs1' (pos 5) not found
  </code></pre>
  <p>I have my code, left and rights images in the same folder. I have read other similar answers but they don't get this error. <em>(<a href="https://stackoverflow.com/questions/28222763/stereo-calibration-opencv-python-and-disparity-map">Stereo Calibration Opencv Python and Disparity Map</a>)</em>. I want to know why this error and how to solve this?</p>