Vision Toolbox Question: Is there a way to access the z-coordinate from the camera calibration process?

Is there a way to access the z-coordinate from the camera calibration process? I wish to perform 3D vector math between calibration planes (i.e., the checkerboard planes shown when using showExtrinsics with plotCamera). The Calibration App shows a 3D plot of all the calibration checkerboards relative to the camera frame of reference (i.e., relative to the camera origin x,y,z = 0,0,0). Clearly, the Calibration App uses a z-coordinate to produce the plot. I would like to access the z-coordinate if available, or calculate it. Thanks for help with this question.

Answer 1

[Dima Lisin]

Hi Thomas,

In the checkerboard's coordinate system the points on the checkerboard all have z=0. If you want the checkerboard points in the camera's coordinate system, then you have to transform them. Let [Xb, Yb, 0] be a point on the checkerboard in the checkerboard's coordinates. The same point in the camera's coordinates would be

[Xc, Yc, Zc] = [Xb, Yb, 0] * R + t

where R and t are the extrinsics associated with that checkerboard. Note that we are using row vectors here.

Answer 2

[Thomas Stepan]

Hello Dima and thank you for the helpful reply to my question.