Fused Location Provider setsmallestDisplacement doesn't work in Android

Question

Hi I have implemented Fused Location provider Api for getting location updates in a service. I was able to get the onlocationchanged event fired according to the interval set. However when i set the setsmallestDisplacement to 10 metres, the event is getting fired even if the device is still. Does any one have problem similar to this. please provide suggestions. Below is the code

    mlocationrequest = LocationRequest.create();
    mlocationrequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    mlocationrequest.setInterval(60000); // Update location every 1 minute
    mlocationrequest.setFastestInterval(10000);
    mlocationrequest.setSmallestDisplacement(10);


    LocationServices.FusedLocationApi.requestLocationUpdates(
            mGoogleApiClient, mlocationrequest, this);

To find the distance between two location values i have used this method.

public static float distFrom (float lat1, float lng1, float lat2, float lng2 ) 
{
    double earthRadius = 3958.75;
    double dLat = Math.toRadians(lat2-lat1);
    double dLng = Math.toRadians(lng2-lng1);
    double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
    Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
    Math.sin(dLng/2) * Math.sin(dLng/2);
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    double dist = earthRadius * c;

    int meterConversion = 1609;

    return new Float(dist * meterConversion).floatValue();
}

But i get the distances as 43.51 , 49.32 , 520.02 even when the device is Still. Is it because the tablet am using in indoor?

Leomaleon

maybe 10m is too small. I've used 50m and I don't get any location updates when the device is still on the table. – Flocculate

Answer 1

If the Displacement is set for LocationRequest, no chance of getting the locations if device is still as Displacement takes precedence over Intervals (interval and fastestInterval). As I could guess - May be you have passed different LocationRequest object (with no displacement set) to LocationServices.FusedLocationApi.requestLocationUpdates().

I was looking for an answer to how locs are received if both interval and displacement set. I just verified for myself with my application and below is the behavior for different configuration for LocationRequest:

1. No Displacement parameter set
   setInterval is set to 1 min and fastest to 1 min.

   I received location every one mins. But you see sometimes it received fast and sometimes slower which is because setInterval is inexact.

06-03 11:46:55.408 25776-25776/ MyLocationListener﹕ onLocationChanged.
06-03 11:47:56.008 25776-25776/MyLocationListener﹕ onLocationChanged.
06-03 11:48:18.768 25776-25776/MyLocationListener﹕ onLocationChanged.
06-03 11:49:22.938 25776-25776/MyLocationListener﹕ onLocationChanged.
06-03 11:50:22.948 25776-25776/MyLocationListener﹕ onLocationChanged.
06-03 11:52:22.978 25776-25776/MyLocationListener﹕ onLocationChanged.
06-03 11:53:22.998 25776-25776/MyLocationListener﹕ onLocationChanged.

2. Displacement parameter is set to 10 meters
   setInterval as above 1 mins.

   No location updates are received if the device does not move or cross that distance. Between every onLocationChanged below I walked more than 10 meters so I received loc.

06-03 11:26:53.328 16709-16709/MyLocationListener﹕ onLocationChanged.
06-03 11:35:38.318 16709-16709/MyLocationListener﹕ onLocationChanged.
06-03 11:39:16.728 16709-16709/MyLocationListener﹕ onLocationChanged.

Ironic

experienced the same..! – Thoma

I have displacement set at 10, setInterval and setFastestInterval set at 3 minutes yet even with significant movement I don't receive regular location updates not sure where is the issue? – Zlatoust

It's depending on whether you are on Cell nw or WiFi. If you're on WiFi, you should get it after 10m walk. If you are on cell, try walking bit more and see. – Ironic

In 2nd scenario its necessary both the condition must be fulfil? – Erythrite

Tnx a lot, this explanation was perfect – Allhallowtide

I think you need to specify here that if Displacement is set to 10 meters and setInterval is 5 mins and user travels 10 meters, still user will receive location update in 5 mins. – Felisafelise

@Ironic Deep what should I do in case I need to consider both the parameters together? for example "every 10 seconds or 50 meters, whichever is true first." – Sinuous

Answer 2

It may happen that you are getting different lat-long in onLocationChanged method which describes more displacement than 10. So kindly checkout the lat-long which you are getting and measure the distance once manually to cross-verify the things.

Apart from above, one more possible reason is matter of priority, If above case seems fine then try like following:

 mlocationrequest = LocationRequest.create();
mlocationrequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
mlocationrequest.setSmallestDisplacement(10);
mlocationrequest.setInterval(60000); // Update location every 1 minute
mlocationrequest.setFastestInterval(10000);

Stuart

I have edited the question with further details.Please go through it once. Also Changed the priority of the statements as you said still the result is same. – Leomaleon

Yes, accuracy does matter. You may checkout accuracy of the location which you get in onLocationChanged method. 10m is very small distance to track. and generally we get the accuracy of 30m most of the time. – Stuart

good point from @MehulJoisar. The accuracy can be off by as much as 100m if you are in a densely populated (with buildings) urban area and/or cloudy day. – Saury

I've found that rain and snow can also really mess up the coordinates – Flocculate

@Saury Deep what should I do in case I need to consider both the parameters together? for example "every 10 seconds or 50 meters, whichever is true first." – Sinuous

@free_style - Not so sure that is easily possible. When setting displacement AND update-interval, the OS will also 'AND' the two. So, once both conditions are met, then the location update will be processed. You can set both, but may have to set a timer and track if an update was made during the elapsed time and then trigger it yourself. – Saury

I tried setting both but the displacement blocks the time-based update. The workaround is to set 2 location requests. Just posting to point someone in the right direction later on. – Sinuous