I don't know what the modern term for what i'm describing would be, we used to call them 'brushes' when making levels for Thief 2 :-)
But if you look at the IMGUR link, it is self explanatory. If you open the building's doors and stand outside, the tent is not visible. If you walk through the threshold of the door, the tent pops into existence.
This was on the Banov map, I don't remember if this building exists on Chernarus or Livonia, but I think it is a Bohemia asset ?
https://imgur.com/a/9kRNDu6 (Just incase I messed the syntax to the link up)