iPhone - Native App GeoLocation VS Web App GeoLocation

Question

Here's my situation; I've built a very simple web app that looks up a users location and plots it on a Google map. Here's my code: http://pastebin.com/d3a185efd

When I test it, my location is detected as being >= 500 meters from where I actually stand.

BUT

When I open up Google Maps or Gowalla my location is correct to within <20 meters?

So my question is: Do native iPhone apps benefit from a higher accuracy rate than web apps?

If so, why?

Answer 1

I think that a webapp relies on a geoip service that (does its best to...) converts your IP address into a GPS coordinate. ex: service ex

However such way to retrieve a coordinate cannot be as accurate as the "classic" one that uses a GPS device (such as the one included in the 3G or 3Gs iphone) to really retrieve your actual location and not approximate it at its best like a geoip service.

UPDATE: GEOIP is used when using google maps on a laptop for instance, but maybe your question was : "when I use the HTML 5 position object in my web page, does it comes from the GPS hardware or from a geoip service ?". This I couldn't really tell, I would say it uses geoip service instead of GPS hardware but I'm not 100% sure...

Answer 2

The code doesn't show where you get position from - are you using Navigator and Geolocation objects?

http://developer.apple.com/iphone/library/documentation/AppleApplications/Reference/SafariWebContent/GettingGeographicalLocations/GettingGeographicalLocations.html

Answer 3

Based on the following link, I believe you are getting coordinates in web app through tower triangulation and not using GPS. I really doubt if GeoIP can give coordinates within 500 meters.

http://phonegap.lighthouseapp.com/projects/20116/tickets/16-navigatorgeolocation-does-not-make-use-of-gps-data

Answer 4

According to the specification, webapp geolocation should use whatever positioning method works best in any situation - so in theory, one would assume it uses GPS when available. The discussion linked in the "best answer" by rohit doesn't seem conclusive to me - here is another one, with someone reporting a similar problem to yours and other users professing to getting accurate gps data (scroll down to comments 26-28 Sept):

http://www.thecssninja.com/javascript/geolocation-iphone

But it does seem like the geolocation stuff is buggy still. I'd suspect your problem is basically that, some bug.

Answer 5

for google geo api first it tries to find your location by device gps , if failed it goes cell triangulation (virtual gps) if failed it try to use to wifi mac and ip addresses , the last try is to use the client IP to get his location