HTML5 GeoLocation by Scott Ryan @ HTML5 user group

Part of HTML5 standard. Not very standard on desktop browsers, but is relatively very stadard on the mobile browsers. Moderizer library helps see what capabilities the browser has

Basics

5 methods to get geolocation :

• GPS : most battery consuming, sky view, elevation possible, better accuracy, 4-x of 24 satellite
• Cell Towers : low power, no sky view, 1-x cell tower, low startup (works well in cities, not in middle of country)
• wifi :
• ip lookup
• assisted GPS
  • cell towers & gps can collaborate to work togather, cell towers can help narrow what satellites to focus on, and delays. cell tower can also do the calculation on the behalf of phone

Cell Towers use : cell towerid : thats what google map uses ( big circle is 1 cid, then multiple cid, circle narrows, pushpin is gps). * other things used : Angle of arrival, time of arrival, signal strength, time difference of arrival etc

Privacy

• prompts the user per domain
• non blocking
• cant bypass via code

Error Messages

• permission_denied : not all browers, some give unknown error
• position_unavailable : can also get if the accuracy asked is high some phone say permission denied

two calls

• getCurrentPosition(function,error_function, options)
  • always get back lat/long, might get altitute
  • accuracy, altitute accurancy (might)
    • speed, heading : no one has implemented
      • options : accuracy, age
  • watchPosition
    • returns the number which is used to stop watching
    • should sample only when locaton changes (significant differences in vendor implementations)

Fall backs

• Geo.js
• GoogleGears : has to be installed
• IP Resolution : yahoo/google has one, few more standard one