The distance between two points selected in a pointcloud exported in rtabmap is actually in metres unit. But initially it would be present as an arbitrary measure. Does anyone know how it is scaled in meters? Is it done in the calculating depth part or in the pointcloud part?
It would even be okay if someone could come up with references in github on where exactly this scaling is done. I've been searching for two days and I could not find exactly where is it.
The camera calibration provides all the info to project depth values (which are in meters) to 3D coordinates in meters. When you calibrate a camera with the checkboard, you should set a size of the square of the checkboard. If that size is in meters, the resulting scale would be in meters.