order of rot_tvec_covariance returned in pose.cc:RefineAbsolutePose()

[Dong Liu]

The name rot_tvec_covariance suggests that it is a 6x6 matrix that the left-upper 3x3 matrix is for rotation covariance and the right-lower 3x3 matrix is for the translation vector covariance.

Am I right?

Thanks,

Dong