Thanks. Got it to work for a 360° rotation on X/Y axis.
The correction of offset and scale works for a pure X/Y calibration.
If I now rotate Z during the calibration too, I get different scaling and offset values for X and Y (not only in total, which would be clear because Z is included but also relative to eachother). With them I don't get a nice centered circle later when I only rotate X/Y.
How do I calibrate X/Y + Z correctly?
Thanks
Robert