Camera calibration and conversion to XML file

C++
1

In order to form a stereo map, I want to get camera calibration information. However, the calibration program in opencv / samples / cpp is difficult for me to write and operate, so I choose to calibrate the camera in MATLAB, but I don’t know how to convert it into opencv readable XML file. If possible, I also want to know for binocular camera extrinsics.yml (XML) and intrinsics.yml (XML) the format of these two files.

Hope to get your help, thank you very much!

2

unfortunately, we cannot help you with that

here’s how a minimal yml file (for a single camera) would look like:

%YAML:1.0
---
camera_matrix: !!opencv-matrix
   rows: 3
   cols: 3
   dt: d
   data: [ 5.3591573396163199e+02, 0., 3.4228315473308373e+02, 0.,
       5.3591573396163199e+02, 2.3557082909788173e+02, 0., 0., 1. ]
distortion_coefficients: !!opencv-matrix
   rows: 5
   cols: 1
   dt: d
   data: [ -2.6637260909660682e-01, -3.8588898922304653e-02,
       1.7831947042852964e-03, -2.8122100441115472e-04,
       2.3839153080878486e-01 ]

(complete file here)
(you’re free to change the names (“camera_matrix”, “distortion_coefficients”) to whatever you like)

to read it back, use:

FileStorage fs("my.yml", 0);
Mat cm; fs["camera_matrix"] >> cm; // or whatever name you used before
Mat dc; fs["distortion_coefficients"] >> dc;
fs.release();
3

Thank you for your reply. I’ll try it further！

4

btw, opencv’s calibration returns (quite weird) distortion coeffs in the format

r1, r2, p1, p2, r3

(r rotational, p positional)

5

Thank you for your reminding. I have completed the intrinsics.yml, However we need R1,R2.P1,P2,Q in extrinsics.yml

image
image1509×1684 268 KB

Do you know what they stand for？

6

explained here