What is rotation_covariance, and relation with {Yaw,Pitch,Roll}_var?

[Frédéric Devernay]

Hi,
There is no documentation on what Metashape.Camera.rotation_covariance represents, so I'm guessing it's the covariance of the axis-angle representation of the camera orientation, a.k.a. rvec, is that right?

I couldn't understand how Metashape.Chunk.exportReference goes from that to Yaw_var, Pitch_var, and Roll_var, even though I computed the analytical Jacobian to go from rvec to YPR (ZXY Euler angles). Did anyone figure out what the correct formula would be? Maybe we could have a better description in the documentation?
I suppose these are standard deviations, not variances of course.
I took the camera orientation in the CRS frame of course.