The Struggles with Location Services

Transcript

1. History of Mobile GPS Phillip Connaughton The Struggles with Location Services {MBLT} Dev ‘15 Phillip Connaughton Principle Engineer @Runkeeper @pconno3
2. History of Mobile GPS Phillip Connaughton Overview • History of GPS on iOS • Runkeeper filtering algorithms • GPS bugs and gotcha’s • Conserving battery life
3. History of Mobile GPS Phillip Connaughton Runkeeper
4. History of Mobile GPS Phillip Connaughton Runkeeper and GPS 1. Collect finite points during the activity 2. Broader location data post activity Used for realtime feedback (distance, pace, calories, etc.) Used for show the general area a user ran in, location based messaging and music
5. History of Mobile GPS Phillip Connaughton iOS 2 • Couldn’t operate in the background • Keeping in foreground demolished battery life • Introduction of ‘Silent Audio Trick’ http://service.o2.co.uk/IQ/srvs/cgi-bin/webcgi.exe? New,KB=Companion,question=ref(user):str(Mobile),CASE=19044
6. History of Mobile GPS Phillip Connaughton iOS 3,4 & 5 authorizationStatus() significantLocationChangeMonitoringAvailable() headingAvailable startMonitoringForRegion(_:) Introduced Region and Heading API’s
7. History of Mobile GPS Phillip Connaughton • Deferred updates • Conserve battery life with Hi-fidelity points iOS 6 https://developer.apple.com/library/ios/documentation/CoreLocation/Reference/ CoreLocationConstantsRef/index.html#//apple_ref/c/data/kCLLocationAccuracyBest https://www.siliconbeachtraining.co.uk/blog/ios-7-new-features - (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray<CLLocation *> *)locations; - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation; • To enable • Set accuracy to kCLLocationAccuracyBest or kCLLocationAccuracyBestForNavigation • Distance Filter kCLDistanceFilterNone - (void)allowDeferredLocationUpdatesUntilTraveled:(CLLocationDistance)distance timeout:(NSTimeInterval)timeout
8. History of Mobile GPS Phillip Connaughton iOS 7 • Background Refresh (no longer impact on location services in iOS 8 and up)
9. History of Mobile GPS Phillip Connaughton Background Refresh
10. History of Mobile GPS Phillip Connaughton iOS 8 Introduction of Location services Authorization CLAuthorizationStatusAuthorizedAlways CLAuthorizationStatusAuthorizedWhenInUse Necessary for region monitoring and for launching apps from the background Great for in the moment location features or tracking
11. History of Mobile GPS Phillip Connaughton iOS 9 & watchOS2 [self.locationManager setAllowsBackgroundLocationUpdates:YES]; Nothing too exciting, changed some permissions watchOS 2 adds CoreLocation watchOS 2 only work when in foreground
12. History of Mobile GPS Phillip Connaughton Setting up Location Services • Setting up location services is really easy func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) { } • Location Services is very noisy self.locationManager.delegate = self //Register your class to receive updates self.locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters // How close do we need to be? self.locationManager.distanceFilter = kCLDistanceFilterNone //We will be informed of any movement self.locationManager.requestWhenInUseAuthorization() // add NSLocationWhenInUseUsageDescription to plist to explain location usage self.locationManager.startUpdatingLocation()
13. History of Mobile GPS Phillip Connaughton Filtering Algorithm • You will not receive points that are as accurate as you asked. While Location Services is starting up you will receive inaccurate points. • Need a large dataset for making real improvements to filters • Important to see every point given by the OS so that you are improving filtering with complete dataset
14. History of Mobile GPS Phillip Connaughton GPS Point • Horizontal accuracy within radius of certainty • Points we throw out • No cell tower points! • Age - are they older than the last point we got?
15. History of Mobile GPS Phillip Connaughton • Horizontal accuracy within radius of certainty • Points we throw out • Acceleration, did the person just jump across the city in a few seconds? • Horizontal accuracy < 0 GPS Point • No cell tower points! • Age - are they older than the last point we got?
16. History of Mobile GPS Phillip Connaughton GPS Accuracy Level Fine grained GPS Data • City Level Accuracy
17. History of Mobile GPS Phillip Connaughton Reverse Geocoding let geocoder = CLGeocoder() geocoder.reverseGeocodeLocation(locations[0]) { (placemarks, error) -> Void in if (placemarks?.count > 0){ let placemark: CLPlacemark! = placemarks![0] if(placemark.locality != nil && placemark.administrativeArea != nil){ NSLog(String(format: "Locality: %@, Area: %@", placemark.locality!, placemark.administrativeArea!)) } } } Geocoder geocoder = new Geocoder(context, Locale.getDefault());
 try {
 List<Address> addresses = geocoder.getFromLocation(latitude, longitude, 1);
 
 if(addresses.size() > 0)
 {
 Address address = addresses.get(0);
 if (address.getAdminArea() != null && address.getLocality() != null)
 {
 Log.d("Location Example", "Locality:" + address.getLocality() + " Area:" + address.getAdminArea());
 }
 }
 }
 catch (IOException e)
 {
 e.printStackTrace();
 } iOS Android
18. History of Mobile GPS Phillip Connaughton Features reliant on GPS and issues they cause
19. History of Mobile GPS Phillip Connaughton AutoPause Don’t want runners to have to mess with phone in armband while running
20. History of Mobile GPS Phillip Connaughton Smoothing with Kalman Filter Normal GPS points Filters GPS points
21. History of Mobile GPS Phillip Connaughton GPS Weirness
22. History of Mobile GPS Phillip Connaughton Android Shuffle
23. History of Mobile GPS Phillip Connaughton Android Shuffle
24. History of Mobile GPS Phillip Connaughton Android Shuffle
25. History of Mobile GPS Phillip Connaughton Android Shuffle Something wrong with sort? Collections.sort(points, new Comparator<TripPoint>()
 {
 @Override
 public int compare(TripPoint lhs, TripPoint rhs)
 {
 return Double.compare(lhs.getTimeAtPoint(), rhs.getTimeAtPoint());
 }
 }); We were setting the timestamps as point.setTimeAtPoint(System.currentTimeMillis()); Returns the current time in milliseconds since January 1, 1970 00:00:00.0 UTC. This method shouldn't be used for measuring timeouts or other elapsed time measurements, as changing the system time can affect the results. Use nanoTime() for that. http://developer.android.com/reference/java/lang/System.html#currentTimeMillis()
26. History of Mobile GPS Phillip Connaughton Elevation We haven’t had much luck with the OS but give it a shot! http://topocoding.com https://www.pinterest.com/pin/320459329711121377/ http://www.cliparthut.com
27. History of Mobile GPS Phillip Connaughton User Presentation Thin Line Thicker Line
28. History of Mobile GPS Phillip Connaughton Battery Life Don’t be here! GPS is a killer Limit network calls
29. History of Mobile GPS Phillip Connaughton Conclusion • iOS and Android continue to make location data easier and easier to use • Consider the users perception when displaying location data to them • Always be thinking about battery life