How to obtain the current location inside a building using an iphone?

Question

I played for a while with the maps framework from the iphone os sdk and the routemap api from cloudmade and it was fairly easy to display the current location and other information on a map by using the data provided by the GPS.

I have the map of a building(airport, mall etc) transformed in tiles of some sort, my question is what would be the best approach to obtain the current position of a phone inside a building? I know that GPS is not accurate inside buildings or might not work at all.

Answer 1

Unless you have a strange sort of building (i.e. radio transparent roof), you will not get a GPS signal inside the building, unless you are close to a window, which there are usually very few of (in a mall anyway).

You will not get useful positional information from cell triangulation (not at mall/airport terminal scale anyway).

I'm afraid I can't see any way to do what you are trying.

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EDIT: come to think of it, some malls do have a glass roof, so it might be possible to get a GPS fix in some places. And some small airport terminals have big glass walls, although you'd be unlikely to want a map if they were very small.