How would I go about figuring the position of someone inside (or outside) of a given area (such as a building) using assisted GPS with IOS app?
Is it possible to have it accurate enough withing a few feet?
Is this the right way to go about it?
Is it possible to utilize more than one wifi connection in the calculation?
Your app can use the Core Location framework to determine the device location. Core Location will use whatever hardware is at its disposal to determine the device location to the degree that you request. For example, some devices have WiFi but no GPS; others have WiFi, GPS, and cellular radios. Future devices may have other location technologies built in.
The point is that as an application programmer, you don't worry about that. Instead, you say: "give me a location that's accurate to 100 meters" or "let me know when the device has moved from the current spot by more than 10 meters" or "give me the location with the best accuracy you can manage."
Again, take a look at Apple's Core Location documentation to get a better idea of how it all works.
If you're looking to track a device with, say, 1-meter resolution inside a building, you're not likely to get that from Core Location. There's been research on triangulating position using known locations of WiFi transceivers, but nothing that's implemented in any commercial smart phone that I know of. I don't believe that iOS gives you easy access to the data you'd need to do this, so it's probably not a possibility. You could, however, go the other way: program several WiFi receivers around the building to listen for any nearby devices, use that information to triangulate the devices' positions, and then make that information available via some web service.
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I've been researching a possible iOS-based app, developed in Unity, that would require a high-degree of positional accuracy (centimeters).
I expect I would need to connect, from the app, to an external GPS device using Bluetooth (or similar) and obtain NMEA sentences (or similar) containing location data.
My research has brought me to RTK, which is extremely accurate. From what I've seen already, it seems that normally GPS receivers which offer this operate themselves at normal GPS precision (2-2.5m). The correction to a high-accuracy location happens in software on a connected computer or tablet with a connection to an NTRIP server.
Assuming what I've said is correct, does anyone know of a GPS device that performs this RTK correction on the GPS device itself? Ideally I could just connect with Bluetooth or similar and get NMEA (or equivalent) data with high-accuracy location.
It may also be that I'm thinking about this incorrectly. On iOS, assuming there is an 3rd party app performing the RTK calculations, is there a standard way to obtain that high-accuracy location? Alternatively, are there GPS vendors that supply SDKs that would allow me to get to where I need to go?
Thanks very much,
Kieran
There is a recent module from U-Blox named ZED-F9P which has internal processing and is faster then RTKLib. Check this blog for performance
You can buy a board like ArduSimple's simpleRTK2B with an XBee module for WiFi/Blutooth or something similar from Sparkfun. You could also wait for the development board from U-Blox which is not yet available.
I'm getting current location,
In my app I want to know my location is from GPS or WIFI or cellular data. How do I check that ?
Is there any way to determine location source ?
Apple iOS uses
Assisted Global Positioning System (A-GPS)
Crowdsourced Wi-Fi
Cellular network search
to determine your location:
These three stages are used in descending order of priority. In other words, iOS first attempts to fix your location by using a GPS satellite link. If it is unable to acquire a satellite, iOS fails over to Wi-Fi. If you are not connected to a Wi-Fi local area network (WLAN), then iOS uses cell tower data
Apple uses all the non-GPS systems simultaneously with GPS, as part of A-GPS. To say it's falling back is not really an accurate description. Rather, while trying to get a GPS lock, it will use the other systems to get a rough idea of your location. Only if no GPS lock can be obtained, will the phone simply report what it knows from the other sources.
CoreLocation does not provide its source (or sources), but you can use some heuristics to guess.
Check the accuracy reported with location updates. A large range (e.g. 500+ meters) would indicate it's not a GPS fix.
Check which radios are available. If there's no cellular radio in the device, fixes must come from Wifi.
Check if the cellular radio is active. The device does not need service with available providers to use towers for a fix. Don't filter on that.
Those are my best guesses. If you really want this feature, you'll have to experiment.
I guess this is a huge flaw in iOS .. like currently it's happening for PokemonGo currently the normal users are able to spoof device location to a desired one in non-jailbroken devices .. any idea or workaround to detect location simulation by Xcode ?
Using GPX location spoofing returns -1 for heading and speed - If your are looking for ways to detect spoofing, if the CLLocationManager is providing Lat,Lngs that are moving, but you're not receiving speed or heading, then the likelihood is the location is being spoofed.
How about using other sets of data to detect GPS spoofing?
Google includes it since 2007.
As an app developer, you could use the phone's internal inertia or orientation tracker data to check your GPS location's plausibility. The built-in compass may also prove useful. Using the phone's internal sensors only won't detect all cases, for example, if they are also spoofed consistently to the GPS signal, but it increases the effort one needs to invest to fool an app successfully. External sources, such as wifi-hotspot locations, would be even better but I think this is pretty much effort on the app developer's side, given that such data needs to be obtained and verified regularly by the application.
An extension on Kento's answer:
If, using accelerometer information, the phone appears to not be moving, request the user shake the device. You can keep a record of how it was shaken, and check if the previous shake was TOO similar. You would have to trial and error what the threshold would be, but I imagine it would be difficult to simulate several different shaking maneuvers.
I wonder if any device has open it's wifi without connect any access point and is it give some data info for geolocation?
Is the question about positioning with WiFi hot-spots ? Basically its described pretty well in: http://en.wikipedia.org/wiki/Wi-Fi_positioning_system
So basically in it, to be ale to determine the location, you must know the positions of the WiFi hotspots beforehand, or at least have a service which has list of hotspots and which could give you the location for the WiFi's you can see.
You don't need to make any connection to the WiFi hotspots, but you simply use the identification they are giving, and passing that information to the part which is determining the position.
In general, you would need to see whether you can find a service you could use from your selected platform, or whether the platform has APIs for using the technology.
In general positioning APIs might use the WiFi information on their cell-based positioning, and on those cases, you wouldn't really need to know anything about the WiFi things in your app.
So I know that there are all these plug-ins for apps that use GPS data, but that is not what I am asking...I wrote a Python library that uses GPS data, and I was wondering if the iPhone stores your GPS data somewhere I can access.
What I want to do:
I essentially want to plug my iPhone into my computer, and generate a CSV of GPS data since I always have location on I figured it might store GPS data somewhere.
I have done research and all that comes up are the different ways to access current locations and use locations in apps, but nothing on how to grab all existing GPS data. Is this possible, and if so, where can I find this data?
iOS itself doesn't store GPS data, actually GPS is disabled by default (as it need a lot of energy, to safe battery life). In fact Developers are advised to use gps only when needed, and when not in use gps hardware get off.
Of course, you could build your own app that could store GPS data when running, also in background, and user will be asked permission to use GPS.
Done this, you could upload/use YOUR app data (not system datas that "probably" don't exist, and if exist are not accessible, anyway)
You can do this only if you upload your own App to iphone which enables GPS and somehow forwards the GPS data.
But you are limited to following GPS attribtes:
time, latitude, longitude, speed, course, altitude, heading (from compass), horicontalAcc. verticalAcc
(Which is sufficient for most applications)