The extrinsics configuration file (extrinsics.ini) is a simple text file used for specifying the extrinsics between the cameras:

phi = 0
theta = 0
psi = 0
T1 = 1
T2 = 0
T3 = 0

The coordinate system is aligned with the optical center of the left camera and is denoted with the figure above.

The extrinsics describe the pose of the right camera relative to the left camera, described by the rotation matrix $R$ and a translation vector $\vec{T}$.

The rotation matrix $R$ describes the rotation of the right camera with respect to the left camera and is assembled following $ZYX$ rotation order - $R = R_{\psi}R_{\theta}R{\phi}$, where the angles $\phi, \theta,\psi$ denote Euler angles around the coordinate axis.

phi: Denotes the pitch or Euler angle of the right camera around the x-axis relative to the left camera

theta: Denotes the yaw or Euler angle of the right camera around the y-axis relative to the left camera

psi: Denotes the roll or Euler angle of the right camera around the z-axis relative to the left camera

The translation vector $\vec{T} = (T_1, T_2, T_3)$ is expressed in the left camera’s coordinate system and describes the translation of the right camera relative to the left camera.

T1: Translation in x-direction

T2: Translation in y-direction

T3: Translation in z-direction

You can perform the Initial Calibration routine to get the initial extrinsic parameters between the cameras.