I developed an app which calculates distances between current position(lat and long) and another stores location. Current position comes from built-in Gps on iPhone. In some buildings is working indoor( like 8meters far from windows or doors). Why is it working indoor? How can I still get GPS signal without WiFi/3G/4G connection?
i hope someone can answer me
Welcome to SO.
The short answer is, it's out of your control. GPS is not reliable indoors. Sometimes you are able to get a signal, sometimes not. Metal frame buildings are worse than wood-frame buildings, and brick also tends to interfere with GPS signals. Florescent lights also tend to interfere.
In a given indoor setting you'll either get a GPS signal or not.
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I need to know if the GPS device component of my users is healthy, so i want to get the location ONLY by the GPS and NOT form wifi or surrounding antennas.
I'm forcing my users to close their wifi before this operation so i definitely know that the received signal is not from the wifi (because its possible).
I tried to work with the CLLocationManager and CLLocation's horizontalAccuracy.
some people say that when the horizontalAccuracy is lower than 160 it means we have a good GPS strength, but its not perfect at all..
I also tried to create an array of [CLLocation] after calling [locationManager startUpdatingLocation], and than i saw that when i'm in a place like a basement(with no GPS signal), my array's count was lower that a situation with signal because the updates frequency is lower.. but this is not a perfect solution either..
I just want to be sure that the GPS component is definitely working and the location that i get is from the GPS.
so, any solution please?
I am working on an iOS app with tracking. I have implemented Kalman smoothing in order to present a pleasing path. This is working pretty well at this point.
I am having a bit of trouble dealing with the user-not-moving case though. When the user IS moving we get very good reads back from the CLLocation Manager. And even when a reading is a bit off the Kalman algorithm takes care of it.
When standing still the CLLocation Manager delegate is still receiving "accurate" locations. They have good accuracy, not an unbelievable speed. Looking at the screen with human eyes it's clear that the user is standing still with all these points just scattered around. Some points very close and a few of them far out.
I have tried setting the CLLocationManager property pausesLocationUpdatesAutomatically but it doesn't seem to be working that well. It doesn't always stop when it should and there have been difficulty restarting the tracking again as the antennas are powered down.
So I'm looking to keep the tracking on the whole time but I want to filter out the jitter in post processing. So I determine programmatically that the user is stopped and discard (or ignore) all locations until the user is moving again.
I'm not really sure how to go about this, what algorithm is appropriate to achieve something like this?
I downloaded the Indoor Atlas iPhone SDK and also generated path maps and test paths for my venue. SDK navigates me perfectly when I am moving from one place to another but when I stop moving it generates scattered output with the position radius from 10 to 25. I am expecting precise co-ordinates in both the above cases in my project.
Is there any way to get more precision?
IndoorAtlas technology is using the history of magnetic field observations for computing the precise location. This means that the device needs to move some distance in order to collect enough data to converge to a correct location estimate, i.e., to have a location fix. We are constantly improving our service to decrease the time needed for the first location fix.
If you experience your position moving after you've already stopped walking yourself, please contact support#indooratlas.com with details of your application and venue where this is experienced and we'll look into it. Thanks!
I have a requirement mentioned below:
Already have a floor plan map image
First detect current location on floor
Then select the destination location using floor plan map image
Now application should provide direction & distance for that source to destination path
This is like how google direction works, but its in-house map require.
For example,
- Current position of user is: At his desk
- Where is Meeting Room #11
- So application should provide direction and distance updates on the map/floor plan image.
Any kind of suggestions/help would be great.
Thanks in advance
Couple of points...
You could create various audio files and play them as way points based on routing. Same principal as 'turn right at the next light'.
Definitely want to set your accuracy to: kCLLocationAccuracyBest. But this will still probably only get you accuracy of around +/- 10 meters at best.
Do a floor plan overlay using MapOverlayView.
If you are indoor, iPhone uses cell towers or WIFI for a location fix. This might be a problem for you because if you are looking to map multiple floors, only GPS can give you altitude readings - ground floor, second floor, etc...
I don't want to pour cold water on your idea but I have not heard of anyone successfully doing an indoor navigation app on an iPhone using standard stuff. If you really wanted to move forward on this project, your best accuracy might be using indoor bluetooth transmitters as navigational beacons...?
What you want is path-planing in the map, is that? If so, there is lot of algoritms you can use. You can choose a block size based on your map and resolution needs, divide de map into this, amd mark each block as navegable or not. Then getting from the first block trying in the direction of the destionation block, check if the neighboor block is blocked or not, and get going, until you reach (or not, if its not reacheable) the destination block.
Thats a pseudo-implementation, you have some option to do it, if I understand your needs.
(I dont know your hardware as said by others, with simple GPS and indoor navigation, assuming a 15m resolution is a good balance between optimistic/pesimistc signal, If its for robot-navigation, its not a goos approach in the GPS terms, but the algorimt is).
I want to know the accuracy and the distance filter of the low-power significant change location service (i.e if I use startMonitoringSignificantLocationChanges how much it's accurate, and what is the distance of the significant change)?
I need some experimental (non documentary) info from real time apps
I had a chance to speak with the Apple Location Engineers at WWDC this past year and this is how it was explained to me.
The significant location change is the least accurate of all the location monitoring types. It only gets its updates when there is a cell tower transition or change. This can mean a varying level of accuracy and updates based on where the user is. City area, more updates with more towers. Out of town, interstate, fewer towers and changes.
This is also the hardest location type to test for since you can't use the simulator either. I'm not sure if they have fixed it to work with the GPX files for 6.0, but the significant location change api did not work at all in the simulator prior to iOS 6.
I have tried to avoid using the signification location change for many of these reasons. Sometimes it can't be helped. I ended up using the region monitoring API's as they are far more accurate and just as good on battery life. Hope this helps.
From the Apple documentation:
This interface delivers new events only when it detects changes to the
device’s associated cell towers, resulting in less frequent updates
and significantly lower power usage.
There doesn't appear to be much more specific information available about the exact accuracy, so I would assume you have accuracy roughly equivalent to the approximate distance between cell towers in the area that the iOS device is currently located in (which is shorter in more highly populated areas).
I had to build an app back then that uses cell tower significant location changes.
Short answer: very inaccurate.
I was clearly crossing the boundaries of my region.
From what we observe in our app, it can be a few hundred metres to a few kilometres off. Our testing was in the city area, cell towers in suburbs parellel to the train tracks and other suburban cell towers.
Pretty rough.
It was consistent most of the time. I notice that every time I was about to go into the tunnel to the underground train station, it would fire off my 3 region crossing notifications that I have setup for the CBD city area.
I'm using Xcode 4.6.2, and you can indeed simulate significant location change on this simulator.
In the iOS Simulator, the menu entries you need are Debug->Location->Freeway Drive.
Caveats (I welcome being told I'm wrong):
1. After a long while, there seem to be no more significant location change events.
2. You can only drive a pre-defined route in the general Cupertino/SF area. If all you care about is significant location change, that's fine.
Be careful, although you can access the speed property of the location got from the significant location update, it's useless! the simulator actually gives the speed but in real devices the speed is not available because location got from cell towers will not include the actual speed(unlike GPS). more the that as said before the location itself is very inaccurate it can be a few km off.
Be aware of that.
The only way to get the speed is have two cllocation and compute the speed manually