title: OpenCV and python to calibrate a camera
body: <p>I'm trying to use OpenCV and python to calibrate a camera.
  This is the OpenCV code: </p>
  
  <pre><code>   CalibrateCamera2(objectPoints, imagePoints, pointCounts, imageSize, cameraMatrix, distCoeffs, rvecs, tvecs, flags=0)
  </code></pre>
  
  <p>Where objectPoints contains all of the "model points". One model point, for each chessboard point found in all of the images. Fill this matrix will the sequential pattern of the board. i.e. (x,y,z) where x=x_co-ordinate of model point, y=y_co-ordinate of model point, and z (normally set to 0) is the depth of the point.</p>
  
  <p>How can I get these "model points" ? </p>