How accurate is possible with IOS and Android through wifi or gps indoors
I am interested in building an IOS app that requires very accurate position tracking of the device while inside of a building. I believe GPS will not be able to handle this, but I am curious how accurate a wifi system can get, using triangulation points and wifi tags. I've seen a few companies talking about this, but no one really put out there exact numbers. I need accuracy down to the inch for my app to work properly. I am comfortable with multiple wifi tags, I just want to know if it's possible with current tech.
If such close accuracy isn't achievable, how close can I get at this point? I can rework the app to function further out, if there is no other way.
GPS can't do that in the best of conditions.
An inch? Forget it. No way. You need phase detection to get that accurate, and even then signal reflection will play havoc with your measurements. Anyway, that would require custom hardware, which is a non-starter for existing devices.
You might be able to get down to a few inches with a very dense grid of iBeacons. You would have to put your beacons every square inch, and then sort all beacons that are in-range for the closest one. You would need to restrict the user's movement to a fixed plane (e.g. keep the phone 2.5 feet off the floor)
As to how accurate you can get, it will be very dependent on the specific room you are using. The materials for the walls/floor/ceiling will have an impact, as will the placement of those walls, plus any electronics that cause RF interference. People in the room will also affect your readings, plus how your user is holding their phone. You're going to have to do careful testing to figure out how accurate you can be.