iPhone and data geolocation accuracy

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iPhone and data geolocation accuracy

Hi everybody,

I'd like to develop an iPhone app that must that locate the user in a museum then popups some useful information about the sculpture he is looking at.

Thus, these questions came to my mind:

How accurate are the longitude and the latitude values ? Because I want to give to each place in the museum this couple of values so that they will be located.
How can set an "error marge" distance in meters (rayon of 20 meters) knowing the longitude and latitude so that I can detect a users's presence?

Thank you,

Regards.

+1 A:

Many museums will have a roof or upper floors that a good GPS signal will not penetrate, so you might not get any more accuracy than the fact they are in the building or neighborhood.

You may have better luck in an outdoor museum with a clear view of a lot of open sky (and thus GPS satellites)

hotpaw2 2010-10-12 18:19:45

Inside a normal building you will not get a GPS signal(unless you are close to a window). If you have a building with glass ceiling it might be possible to get a GPS fix.

From cell triangulation you will not get useful positional information either.

How accurate are the longitude and the latitude values ? Because I want to give to each place in the museum this couple of values so that they will be located.

outside, these values are pretty accurate 1-2 meters error at most.

SorinA. 2010-10-12 18:29:11

Thank you for your answer. But how can I detect if the user is at 2 or 3 meters from the sculpture?

Zakaria 2010-10-12 19:40:15

if you could get the current location(lat/long) you could compute the distance between that and the sculpture position(lat,long). lets say in a room you have 5 sculptures. you need to determine their location(lat, long), store them and when the gadget detects movement to see if in his rage are sculptures. if they are which is closest and maybe use bearing to see in which direction the user is moving in order to load info more precise. for computing distances between lat/long points you can use http://www.movable-type.co.uk/scripts/latlong.html

SorinA. 2010-10-13 06:56:48

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iPhone and data geolocation accuracy

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