The file calib_cam_to_cam.txt contains parameters for 3 cameras.
- S_0x: is the image size. You do not really need it for anything.
- K_0x: is the intrinsics matrix. You can use it to create a cameraParameters object in MATLAB, but you have to transpose it, and add 1 to the camera center, because of MATLAB's 1-based indexing.
- D_0x: are the distortion coefficients in the form [k1, k2, p1, p2, k3]. k1, k2, and k3 are the radial coefficients, and p1 and p2 are the tangential distortion coefficients.
- R_0x and T_0x are the camera extrinsics. They seem to be a transformation from a common world coordinate system into each of the cameras' coordinate system.
- S_rect_0x, R_rect_0x, and P_rect_0x are the parameters of the rectified images.
Given all that, here's what you should do.
- Pick two cameras of the three, that you want to use.
- Create a cameraParameters object for each camera using the intrinsics and the distortion parameters (K_0x and D_0x). Don't forget to transpose K and adjust for 1-based indexing.
- From the extrinsics of the two cameras (R_0x's and T_0x's) compute the rotation and translation between the two cameras. (R and t).
- Use the two cameraParameters objects together with R and t to create a stereoParameters object.