Position relative to what?

[Romulator]

Well, I know you're working with Penumbra, but I turned to AAMFP assets to look at sizes.

The 4x8m road which can be found in the streets for static_objects is what I used in this example.

I took the long side of the road and put it down at 0,0,0, without rescaling or rotating. At 0.25 snap, there are 32 squares along the Z-Axis. At 0.5, there are 16, and at 1.0, there is 8. Therefore having a 1.0 set as the snap sep. is equivalent to 1m.

Not ENTIRELY sure if it is the same for Penumbra, because I cannot develop with those if I don't have the game () but those were my findings with that

Edit: And no, not arbitrary. It is primarily the centre point of the whole map, the area which can be seen first in the perspective view, where the 3 Axis cross over (again, do not know if this is in Penumbra's dev tools).