In Brandon Sanderson's novella Snapshot, the Snapshot is implied to occupy real space underneath New Clipperton.
“they’d decided not to remove the installation built underneath it.”
It's also described as having a boundary
“If people left the area the Snapshot covered, they vanished immediately.”
Towards the end of the story, it is revealed that the action has taken place within a 'Snapshot of a Snapshot'.
Does this mean each Snapshot also recreated the area beneath the city?
If this is true, and the Snapshot occupies physical space, then surely the area the Snapshots recreate would appear to be infinite, or does it just have to stop at some point?