Camera Calibration with the help of MATLAB toolbox

In order to get an accurate result from disparity to depth, we need to know the intrinsic parameter, such as focal length and skew coefficient, for our camera. So we use the Caltech Camera Calibration toolbox to get those parameters for the two cameras separately.

We take around 200 pictures with the checkerboard and pick up 12 pictures for calibration for each camera. And then follow the instruction on the website to obtain the parameters.

Picture.1 calibration images

Picture.2 extract the grid corner

And here is the result of calibration:

Calibration results (with uncertainties):
Focal Length:          fc = [ 1762.62339   1771.13354 ] ± [ 33.53921   33.64017 ]
Principal point:       cc = [ 657.10654   494.14503 ] ± [ 45.24948   41.64433 ]
Skew:             alpha_c = [ 0.00000 ] ± [ 0.00000  ]   => angle of pixel axes = 90.00000 ± 0.00000 degrees
Distortion:            kc = [ -0.24440   0.25448   0.00050   -0.00360  0.00000 ] ± [ 0.06230   0.19754   0.00330   0.00715  0.00000 ]
Pixel error:          err = [ 0.25417   0.35936 ]

The links for the website for the calibration toolbox is as follows:
http://www.vision.caltech.edu/bouguetj/calib_doc/htmls/example.html

And we would like to use the extrinsic parameters( such as rotation and translation) from the toolbox, to help us to adjust the relative motion between our cameras as well.