Buildings have no satellite signal and no tactile map.

Outdoor navigation is a solved problem compared with a hospital corridor. There is no GPS indoors, signage assumes you can read it from across the hall, and the layout gives you no clue where you are. Phoenix Eye works from what it sees — door frames, corridor junctions, room numbers, lift panels — and keeps a running sense of where you turned. Testers navigated an unfamiliar clinic wing from the entrance to a named room, unaccompanied.