Will the GPS cordinates be accurate enough to build an app which helps the user to navigate inside a building? Ex: to give path to the EXIT, to give path to navigate to a wash room, different section etc?
Not in all buildings GPS even work, and, when outside, it is not precise enough without additional stations.
Typical GPS precision is 10-12 meters.
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Presume I have two+ iPhones connected to the same server.
Using the sensors built in the iPhone and any possible calculations based on their information, is there any way to tell which direction one phone is from another?
They would be in the same room, so the fluctuation of GPS would not work very well here.
I've tried to model two points on a graph using only their compass readings, but I do not think this will work alone. I could be wrong though.
You could setup a calibration phase in your program where you start each phone in an exact position, and then using the 6 axis motion continually calculate the exact current position (in all 6 axis). But the longer you run that calculation the further from true position you will be and eventually (given a long enough time) one phone could think it's in canada and the other in Mexico.
So It could work for short term spurts if you do a calibration every time you want to start.
There is also the possibility of bluetooth localization, but that would require at least 3 phones and the sharing of positional data between them. Or you could do wifi location, but that would require the same as the bluetooth.
Long story short if you want inches localization it's not going to happen. If you want yards localization it's possible, but not as usable.
As you already mentioned, GPS does not work very well when used inside buildings. Thus, it is not possible to get the direction, as you don't have two reliable positions.
Indoor localisation should be much easier with iOS7 and location beacons .. but this does not help much now.
quick question. How accurate is the GPS on the iPhone 4? I ask because I'm working on an enterprise project for a company, and part 2 of it will deal with iDevice development where I have to determine the position of the user. I'd like to know if the GPS is accurate enough to sense the user moving within rooms because the user will have to "tag" sections of the room as they move about it.
Thanks in advance!
P.S. Pressuming that it won't make much of a difference, but the users will actually end up using the iPads, not iPhones, and more than likely the iPad 2 will be out by the time the entire project is completed. I don't know if the iPad 2 will have a better GPS receiver or not, but at the minimum I should use the iPad/iPhone 4 GPS receiver...
Most buildings will not allow reception of an accurate set of GPS signals (if they can be received at all) indoors. The roof/ceiling/floors above are just too thick. Even a lot of trees overhanging a building will degrade the signal from the GPS satellites.
You might have a chance if all the rooms have very large unobstructed windows with no overhangs, and it's the right time of day for several satellites to be in view out that window.
Outdoors, in the clear, the iPhone 4 GPS seems to be very accurate. Sometimes I can walk around my parked car, and see the blue dot in the Maps app follow me in a circle.
I have done some work with a large location data set. My result set is based on cars driving outside and will therefore be, on average, more accurate than those taken inside (based on line of sight to satellites).
For the 650,704 location updates I used in my tests, I found the average accuracy radius was 246m (91m if your remove >1km outliers). 85.1% of updates had an accuracy of less than 100m. So given that your update will not be as accurate as these, I don't imagine you will have much success tracking indoor location changes.
For a further description of my results.
It is very difficult, and most of the time impossible to obtain a GPS signal inside a building. The type of waves used by the GPS (radio waves) are not powerful enough to go through the structure itself.
A simpler and probably cheaper solution would be to give people maybe tags or cards and install some sort of trnasreceiver in each room.
It seems the original question was "how accurate is the GPS on an iPhone 4", which hasn't exactly been answered yet.
I've done lots of testing with the accuracy of the GPS chips in iPhone 4, iPhone 4s, and iPhone 5, and the most accurate reading allowed seems to be ~5 meters, or ~16 feet when you're outside with clear line of sight to the sky. I'm guessing this is a software limitation imposed by Apple to conserve battery.
I am trying to find the location of user using corelocation framework in my app ,
but
it doesn't showing good results , can anyone please tell me how can i get location accurately in indoors ?
thanks in advance
regards
I am not sure, about the exact physical environment but if wifi access points are available then you can use sdk available from skyhook wireless or navision to locate your current position in case the accuracy of the gps position is not good.
This is not a failsafe approach, but may work better in areas where data is available about wireless ap.
In the general case, you can't get an accurate location indoors using Core Location. (What's wrong with your question is in assuming that you can, before asking how to do the impossible.)
You might get lucky if you are under to a tent roof that is paper thin or near a large window below lots of wide open sky, or happen to be between 3 or more nearby wifi access points whose locations are all accurately and precisely registered with whichever wifi database(s) Apple is using.
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.
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.
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.
If you are able to install a few WiFi nodes inside a building, you can get your location inside this building with Navizon's Indoor Positioning System.
They have a demonstration video of their indoor navigation solution on an iPhone.
Since you can't use GPS or Cell towers, you'll need some other sort of RF sources, that have known positions (as GPS and Cell Towers do) Perhaps that's what you're targeting anyway, something like a mall or airport with a number of WiFi routers in known locations, that you could "ping" off. It's not that simple of course --- an interesting research paper on such a service is at Microsoft Research: In fact they write about possible applications such as malls or airports.
Indoor Atlas maps magnetic fields in buildings and then uses smartphone magnetometer data to geolocate indoor locations to within 2 meters. It's based on the fact that buildings have predictable magnetic fields due to the materials they are constructed with. It's the best solution I've seen for this. You can try it for free as see if they've mapped the particular buildings you're trying to geolocate inside of. Another solution I've seen requires bluetooth devices within the building to assist with the geolocation, not as good because of the infrastructure requirements.
I have been programming an app using the mapkit and the SDK 3.0. Everything works allright except for one detail. I have noticed that when displaying the userlocation I get different user positions on the map dependent of the current network. I have read about this problem and understand that it is common? In my WLAN is the user position correctly displayed. When using the 3G net (T-mobile) the position is some 100 meters away from my actual position. I understand this has to do with the celluar phone net using triangulation and in WLAN is the GPS or WiFi hotspot used. So, to my question. Is there a way to go around this? My app shows positions in a town and also the distance to those positions. It is very obvious and also missleading if the position is false because of the short distances. Is there a way (in code) to set which method to be used for getting the user postion? I have tested all other apps on my iPhone using maps and the problem seem to be the same by all of them. (If someone wants to test my app it is in the app store for free under car2go also other comments are of course interesting)
Thanks in advance!
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Core Location provides information about the vertical and horizontal accuracy of the location that it is reporting. One should use that accuracy to report to the user if the location is suspect. Google maps does this by increasing the size of the blue circle around the location marker. There are other ways to indicate to the user that the location is suspect, alert boxes, not showing the location if it falls outside of some predetermined accuracy, etc.
See: http://developer.apple.com/iphone/library/documentation/CoreLocation/Reference/CLLocation_Class/CLLocation/CLLocation.html#//apple_ref/occ/instp/CLLocation/horizontalAccuracy
Use an alternate source for your location? Portable GPS units would do the trick.
The real question is how can you correct the data being specified by the 3G triangulation. I wonder if you can do a differential to correct for the 3G's location errors.
1) In a given city, calibrate the 3G location errors by plotting the city. This could be corrected by the 3G networks at any time, so you'd have to have a way to verify and re-calibrate.
2) Calibrate the 3G network's location using a known location - a 3G location along with a GPS location. Take that as a differential that can be applied to other 3G locations. This assumes a consistent offset in the triangulation calculation which probably isn't the reality.
3) Wait for the 3G networks to fix it and do nothing in the meantime.
4) Provide the 3G network provider with error information in their triangulation and see if it is a priority for them.
I can't think of any other viable options...
Perhaps you can use CoreLocation directly. CLLocationManager gives you CLLocation objects than include their accuracy. If you get an accuracy below 50 meters, it the location probably came from GPS.