Extrinsic Calibration Reference Point (Multiple Camera)

[JonasWenke]

Hi,

I am currently performing an extrinsic calibration between two cameras. For measuring the translation (e.g., in a CAD model), which reference point in the cameras should I use? Determining the X-axis (horizontal) and Y-axis (vertical) measurements is relatively straightforward, but I need the exact reference point in the camera to accurately measure the translation along the Z-axis (depth).

Does anyone have any guidance on how to find or define this reference point?

Thank you in advance for your assistance.