html5 geolocation accuracy

Question

Hi,

Just a quick question I have built the following code:

http://letterpool.testmode.co.uk/map.html

However with some users I am getting reports that people are getting around a 200-300 meter of their actual location.

Does any one know why ?

Answer 1

Because geo-location is not accurate and never has been. They are probably getting the location of the closest junction box.

With me, it found the data center where my ISP operates from - miles away.

See this article.

Answer 2

Geolocation of course depends on the available position measurement methods. If the browser only has the IP address then it will be very inaccurate, but if it has access to a a GPS device like in a smartphone it will be pretty good.

Answer 3

The W3C Geolocation API, which you're using to locate users on the test map, is intentionally agnostic to the method the browser uses to locate the device. This is a useful convenience since devices vary widely on how they locate (GPS, WiFi triangulation, cell tower triangulation, IP geolocation, manual entry, etc.) and your website probably doesn't want to deal with all of those details.

However, if you're not happy with the accuracy, there are a few options you can take advantage of that may help. The enableHighAccuracy option will hint to the device that it should prefer to use up a little more power in order to get a more precise location. You're currently using the latitude and longitude of the return value, but the API also returns an accuracy value, so you can see whether the position you're receiving is precise or not. You could also use watchPosition which will continually update the location and may eventually get a precise enough fix for your purposes (most mobile devices tend to start with low accuracy and get more refined over a few seconds or minutes).