How to interpret the results of the calibration (OpenCV)

Question

I performed the calibration with chessboard (I defined the size of the corner in mm). Now, are the results of the calibration (matrix roto translation) in mm?

Answer 1

Short and long answer: yes.

You basically set the units when you define the chessboard square size, so since you defined it in mm, your results will be in mm.

Edit: Keep in mind though that the reprojection error is in pixels and not in mm.