title: camera coordinate to pixel coordinate opencv
body: <p>I am confused about the opencv camera calibration coordinate transformation. I used the example code to calibrate my camera, and I got this result:</p>
  
  <p><a href="https://i.stack.imgur.com/q5afN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/q5afN.png" alt="enter image description here"></a></p>
  
  <p>When I use this camera matrix to multiply a point in camera coordinate system, say P = [50, 50, 1.35], the output result is too big which is impossible to be a pixel coordinate. What's is wrong here ? Did I miss something ?</p>
  
  <p>The image is 1920 x 1080. This is the chessboard configuration file information:</p>
  
  <p><a href="https://i.stack.imgur.com/IDqA1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IDqA1.png" alt="enter image description here"></a></p>