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https://github.com/smidm/video2calibration

Camera intrinsic parameters calibration from chessboard video sequence.
https://github.com/smidm/video2calibration

camera-calibration opencv video

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Camera intrinsic parameters calibration from chessboard video sequence.

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README 

        
[![Build Status](https://travis-ci.com/smidm/video2calibration.svg?branch=master)](https://travis-ci.com/smidm/video2calibration)



Camera Calibration Using OpenCV

===============================



Python scripts for camera intrinsic parameters calibration and image undistortion.



It finds following parameters:



  * focal length

  * principal point

  * radial distortion coefficients



using video of a moving chessboard pattern or a sequence of images as an input.



Example input: 



![input video](doc/input_video.jpg "Screenshot of an input video.")



Example output YAML file:



~~~

camera_matrix:

- [1016.5691777733053, 0.0, 632.3505845656954]

- [0.0, 1013.9401023559311, 351.0453222243043]

- [0.0, 0.0, 1.0]

dist_coefs:

- [-0.3797582960152331, 0.20896823985868346, -0.0003239082442461539, -0.0019027617884934114,

  -0.0668551319250156]

rms: 1.1814231691868478

~~~



Installation

------------



```

pip install video2calibration

```



You can also install the in-development version with::



```

pip install https://github.com/smidm/video2calibration/archive/master.zip

```



Camera Calibration

------------------



 1. print the [pattern](pattern.png) without any distortions

 2. check if the printed squares are correct squares

 3. glue the pattern to a solid board

 4. fix the camera lens zoom, the calibration values change with the lens zoom changes

 5. record a video with the pattern moving in front of the camera

    * the pattern should be most of the time completely visible

    * try to move the pattern to cover all parts of the camera view, pay attention to the corners

    * the length of the video should be 1 or 2 minutes

 6. run the calibration.py to extract chessboard pattern corners from the video and perform camera calibration



Example usage (you can actually run the example, the input data is present in the ./example_input):



~~~

$ calibrate.py --help

usage: calibrate.py [-h] [--debug-dir DEBUG_DIR] [-c CORNERS] [-fs FRAMESTEP]

                    input out



Calibrate camera using a video of a chessboard or a sequence of images.



positional arguments:

  input                 input video file or glob mask

  out                   output calibration yaml file



optional arguments:

  -h, --help            show this help message and exit

  --debug-dir DEBUG_DIR

                        path to directory where images with detected

                        chessboard will be written

  -c CORNERS, --corners CORNERS

                        output corners file

  -fs FRAMESTEP, --framestep FRAMESTEP

                        use every nth frame in the video



$ mkdir out

$ calibrate.py example_input/chessboard.avi calibration.yaml --debug-dir out

Searching for chessboard in frame 0... not found

Searching for chessboard in frame 20... not found

Searching for chessboard in frame 40... not found

Searching for chessboard in frame 60... not found

Searching for chessboard in frame 80... not found

Searching for chessboard in frame 100... not found

Searching for chessboard in frame 120... not found

Searching for chessboard in frame 140... ok

Searching for chessboard in frame 160... ok

Searching for chessboard in frame 180... ok

Searching for chessboard in frame 200... ok

Searching for chessboard in frame 220... ok

Searching for chessboard in frame 240... ok

Searching for chessboard in frame 260... ok

Searching for chessboard in frame 280... ok

...

Searching for chessboard in frame 1980... ok

Searching for chessboard in frame 2000... ok

Searching for chessboard in frame 2020... ok

Searching for chessboard in frame 2040... not found

Searching for chessboard in frame 2060... not found

Searching for chessboard in frame 2080... not found

Searching for chessboard in frame 2100... ok

Searching for chessboard in frame 2120... not found

Searching for chessboard in frame 2140... not found

Searching for chessboard in frame 2160... not found

Searching for chessboard in frame 2180... not found



Performing calibration...

RMS: 1.01973939405

camera matrix:

[[ 774.55857698    0.          619.69416634]

 [   0.          772.96410156  352.49790333]

 [   0.            0.            1.        ]]

distortion coefficients:  [ -3.65385859e-01   1.63224385e-01  -2.67163331e-03   3.38261891e-04

  -3.81711948e-02]



~~~



Removing Radial Distortion

--------------------------



You can test the found radial distortion coefficients by removing distortion from an image and checking if straight lines are really straight.



~~~

$ undistort.py --help

usage: undistort.py [-h] calibration input_mask out



Undistort images based on camera calibration.



positional arguments:

  calibration  input video file

  input_mask   input mask

  out          output directory



optional arguments:

  -h, --help   show this help message and exit



$ undistort.py calibration.yaml 'example_input/*.png' out/

processing example_input/distorted.png... ok



~~~



Development

-----------



To run all the tests run:



```

tox

```



License

-------



MIT License, except `pattern.png` from OpenCV (3-clause BSD License).