Aruco - Marker

[AleAsc27]

Where can I find more information how to use Aruco marker?
I've done some tests but it's not very clear how stella_vslam is using these marker.
It would be nice to be able to use these markers to apply a metric scale to the reconstructed paths.
In addition to being able to position the marker position on the reconstructed path.
It's possible? I have done several tests but I cannot understand how they are managed.