To simplify, if you have a map of Ankh-Morpork on your wall and you put your finger on Sator Square, your finger is not in Sator Square, no matter how detailed the map is. If you moved your finger around on the map, you would not know what would happen if you moved your finger around in Ankh-Morpork, nor whether it's safe to do so, no matter how detailed the map is.