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I'm doing a project that requires acquiring real world coordination from a camera. The first thing that I need to do is calibrate my camera. I use Camera Calibrator from MATLAB Toolbox, and about 40 samples for calibrating. All the samples was taken by Logitech C922. But after calibrate, the result seems so wrong, as you can see in the image below. enter image description here

It is more distortion than the original image. I have also tried to calibrate using OpenCV but the result is the same. Anyone know what wrong and why does this happen ?

I am sorry if those questions are really beginner level, camera calibration is very new to me and I was not able to find my answers.

Thank you in advance!

Trung Tran
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    Very hard to tell without looking at your images. Can you please upload them someplace and send a link? – Francesco Callari Mar 27 '17 at 04:11
  • Thank you for your reply. Here are all the images that I use for calibrating.[Calibrate Images](https://drive.google.com/drive/folders/0B4-imQMI5JvHck5lZFZhbk9zRDQ?usp=sharing) – Trung Tran Mar 27 '17 at 08:03
  • You have only rotation in one axis, and the board is very far from the camera. Try rotating in the other axes, and try to take up more of the frame for the board. – Photon Mar 27 '17 at 09:42
  • Suggest you follow this recipe: http://stackoverflow.com/a/12821056/1435240 – Francesco Callari Mar 27 '17 at 23:04
  • @Photon Thank you for your reply. So, should I bring the board nearer the camera than before, or use another bigger one? Thank you in advance. – Trung Tran Mar 28 '17 at 16:20
  • it doesn't matter which, as long as it takes more of the frame. But much more important is the variety of rotations. – Photon Mar 28 '17 at 18:17

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Firstly, you really need to figure out what does 'calibration' means. it's clear that the picture is showing the undistorted picture,since the lines on the chessboard and those on the background are quite straight. Without undistortion the chessboard in the center would look like squeezed in radial directions. Check the button 'show original' on the bottom-left corner of your picture, click it, and find the difference between these two pics.

What this calibrator does is that it calculates the intrinsic/extrinsic parameters, distortion coefficients and, if you wish, undistort the pictures you gave to her. She already did the job.

Jiawei Sun
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