MarkB
Legend
Viewing angles might put lightly obscured squares between you and a given observer, but since you've made your check up front...
...do you need to be comparing with Perceptions square by square? Or can that be done up front too?
-vk
Good point. But those are modifiers to the observer's Perception check, not to the rogue's Stealth check. You'd need to be prepared to take it square by square, if the rogue's roll was low enough that an opponent's unpenalised Perception check would detect him.
That is one of the advantages of running it as written - you already know which route the rogue took by the time the check is made. The question is whether the increased sense of realism gained by not having to 'wind back' the rogue's move for an interruption is worth the increased hassle of tracking Perception modifiers square by square.