Advanced Geolocation for the Mobile Web. Andy

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Malcolm Shelton
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1 Advanced Geolocation for the Mobile Web Andy

2 How to get a good location Challenges Solutions

3 Smartphone/Tablet GPS Built for consumer use-cases Accuracy only needs to be good enough Tiny antenna on bottom of device

4 Geolocation Object

5 Say what, 4887 meters accuracy??? Indoors using WiFi-only

6 Demo

7 Best possible accuracy under perfect conditions 3 10 meters feet

8 Problem 1: location fluctuations

9 Problem 2: all locations lumped together Network location GPS location

12 ??

13 Use case: Stationary 5 minutes!

14 Problem 3: Accuracy will vary Bad Time vs Accuracy So-so Good

15 Problem 3: Accuracy will vary Bad Time vs Accuracy So-so Good

16 Accuracy vs Precision Low Accuracy High Precision High Accuracy Low Precision High Accuracy High Precision

17 Problem 4: GPS needs to warm up! Initial readings less accurate or non-existent

18 Technical Use Case: Cold Start GPS takes time to calibrate Phone rebooted Updated phone OS Potential for no cached values Potential for large inaccuracy

19 Technical Use Case: Warm start GPS has been in use continuously GPS is (mostly) calibrated Highest potential for accuracy and precision

20 Using the Geolocation API options errorhandler() Timeout maximumage used only during startup enablehighaccuracy

21 Snapshot location Not Reliable! navigator.geolocation.getcurrentposition();

22 Continuous location watchid = navigator.geolocation.watchposition( processgeolocation, /* OPTIONAL */ geolocationerror, { timeout: 0, maximumage: Infinity, enablehighaccuracy: true } );

23 maximumage (ms) Max age of cached position in milliseconds 0 do not use cache Infinity (default) return any cached value

24 timeout (ms) Max milliseconds to return a position Throw error if no location at timeout With watchposition() can throw error repeatedly Infinity (default) don t return until position available

25 enablehighaccuracy(boolean) Try to obtain best possible result If GPS available and perms enabled -- use it If Geolocation Service available -- use it Requires an internet connection! WiFi and/or Cellular

26 watchposition scenario 1: Request result < 30 seconds Accept cache value < 5 mins old { } timeout: 30000, maximumage:

27 watchposition scenario 2: Request result < 1 minute Return any cache value { } timeout: 60000, maximumage: Infinity

28 watchposition scenario 3: Request result < 1 minute Do NOT use cache, try GPS { } timeout: 60000, maximumage: 0, enablehighaccuracy: true

29 Browser Geolocation Accuracy Depends on Type of browser Type of device Wi-Fi On/Off GPS On/Off Location user permissions VPN

30 Force phone to use GPS

31 Solution 1: Solution 2: Solution 3: Post-process buffering Cordova plugin 1 and/or 2 + external GPS

32 Solution 1: Buffering to determine center point Capture many points Average all values Calculate centroid [{lat:-120,lon:35}, {lat: ,lon:35.1}, {lat: ,lon:35.02}, {lat:-120,lon:35.1}, {lat:-120,lon:35}]

33 JavaScript Data Collection Field location template github.com/esri/html5- geolocation-tool-js

34 Solution 2: Cordova/PhoneGap & Geolocation Taps native SDKs via plugins Direct access to geolocation functionality Can track geolocation while in background Battery usage optimization

cordova-plugin-advanced-gelocation https://github.com/esri/cordova-plugin-advanced-geolocation Android only!

35 cordova-plugin-advanced-gelocation Android only! Separates GPS from Network location Native functionality Multi-threaded for high performance Calculates centroid Separates network locations from GPS locations

36 External GPS Can provide greater accuracy and precision Can provide faster location acquisition Connect via USB or Bluetooth

37 Example: Trimble R1 Sub-meter accuracy* Works with Geolocation API Overrides onboard GPS Works on ios and Android

38 On extra step on Android

40 A GPS Experiment START POINT

41 Commercial GPS Smartphone GPS

42 Solution 3: buffer, plugin + external GPS Take a close look at use cases Study your requirements

43 Recap Consumer vs Commercial case cases Consumer vs Commercial equipment Accuracy vs Precision Getting the best static location

44 Questions? Andy Gup, Esri Developer Advocate

45 Works with..

46 Works with

Building Native Mapping Apps with PhoneGap: Advanced Techniques Andy

Building Native Mapping Apps with PhoneGap: Advanced Techniques Andy Gup @agup Agenda Application life-cycle Working with UI frameworks Security Geolocation Offline Expectations Experience with PhoneGap