Regardless of the API there is no magic involved here. The physical GPS
hardware has to be active at all times to provide that level of accuracy
(and you have to have sufficient sky view too). That comes at a cost,
specifically to the battery. The OS is likely trying to reduce that cost by
switching to the more readily available lower cost cell triangulation
position.
On Saturday, March 7, 2015 at 5:28:53 PM UTC-5, Tony Pitman wrote:
>
> I wrote an app that uses location services. It creates a geofence around
> my house and lets my app know when I come home. I am doing this in a
> service in the background so that my app doesn't have to be the active app
> to function. I was using the LocationManager api.
>
> I have a Samsung Galaxy Note 2 with Android 4.1 on it.
>
> The app was working perfectly.
>
> I upgrade the phone to Android 4.3 because it just became available.
>
> Now all of a sudden my app started getting notifications that I was
> outside of the geofence when I was still inside and not even really moving.
>
> I did some searching and saw a video presentation from the Google IO
> conference in 2013. It talked about the new Google Play Services (at the
> time new) and all the great stuff they were doing with location.
>
> I decided to switch to that because it seemed like a better way to go.
> When I studied the api I found that even the stuff in that video was
> deprecated and there was newer stuff. I got excited thinking it would solve
> my problem of accuracy.
>
> I just finished implementing my app using the Google Play services
> Geofencing. Guess what? I have the same problem.
>
> I put in some logging and basically here is what happens:
>
> I use the Fusion request for location updates to figure out where I am. I
> first look for an accuracy of < 10 meters for at least 5 samples. This is
> done because my radius is 80 meters, so I have to have a high accuracy when
> starting out.
>
> Once I get that I turn OFF the location updates and set up the geofence. I
> use the location of my house that was previously gathered from a mapping
> piece of my app with a radius of 80 meters. I would like to be able to go
> down to 20 meters if I can get it working, but 80 for now.
>
> When I first create the geofence I get 2 notifications right away. The
> accuracy on those events is 3.8 meters.
>
> I then let the app sit for about a minute.
>
> At that point I then get 2 more transition events. Both of them say I am
> outside of the geofence. The accuracy on these events is 2373 meters.
>
> I can only assume that after a minute the api has switched to a lower
> accuracy system for some reason.
>
> I then walked at least 80 meters away from my house and I never got any
> more transition events at all.
>
> The question is what do I do about it? My app is even still the active
> app, so this is not a background issue. I assume it might even be worse if
> I was in the background.
>
> I have requested the highest accuracy.
>
> I have heard people say that the answer to this problem is to leave a
> location update request going. Doesn't the defeat the whole purpose of
> letting the api take over for us? Shouldn't I be able to say I need high
> accuracy geofencing and the api just takes care of it?
>
> Here are some snippets from my code:
>
>
> public synchronized void buildGoogleApiClient() {
>
> _googleApiClient = new GoogleApiClient.Builder(_context)
>
> .addConnectionCallbacks(this)
>
> .addOnConnectionFailedListener(this)
>
> .addApi(LocationServices.API)
>
> .build();
>
> }
>
> Geofence geofence = new Geofence.Builder()
>
> .setRequestId(door.Id)
>
> .setTransitionTypes(Geofence.GEOFENCE_TRANSITION_ENTER |
> Geofence.GEOFENCE_TRANSITION_EXIT)
>
> .setCircularRegion(door.Latitude, door.Longitude, door.
> ActivationDistance)
>
> .setExpirationDuration(Geofence.NEVER_EXPIRE)
>
> .build();
>
> GeofencingRequest geofenceRequest = new
> GeofencingRequest.Builder()
>
> .addGeofence(geofence)
>
> .setInitialTrigger(door.IsInside ? GeofencingRequest.
> INITIAL_TRIGGER_ENTER : GeofencingRequest.INITIAL_TRIGGER_EXIT)
>
> .build();
>
>
> LocationServices.GeofencingApi.addGeofences(_googleApiClient,
> geofenceRequest, pi);
>
>
--
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
---
You received this message because you are subscribed to the Google Groups
"Android Developers" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
