How does Google calculate my location on a desktop?
I am currently in Tokyo, and I used to be in Switzerland. Yet, my location until some days ago was not pinpinted exactly, except in the broad Tokyo area. Today I tried, and I appear to be in Switzerland. How?
Well the secret is that I am now connected through wireless, and my wireless router has been identified (thanks to association to other wifis around me at that time) in a very accurate area in Switzerland. Now, my wifi moved to Tokyo, but the queried system still thinks the wifi router is in Switzerland, because either it has no information about the additional wifis surrounding me right now, or it cannot sort out the conflicting info (namely, the specific info about my wifi router against my ip geolocation, which pinpoints me in the far east).
So, to answer your question, google, or someone for him, did "wardriving" around, mapping the wifi presence. Every time a query is performed to the system (probably in compliance with the W3C draft for the geolocation API) your computer sends the wifi identifiers it sees, and the system does two things:
- queries its database if geolocation exists for some of the wifis you passed, and returns the "wardrived" position if found, eventually with triangulation if intensities are present. The more wifi networks around, the higher is the accuracy of the positioning.
- adds additional networks you see that are currently not in the database to their database, so they can be reused later.
As you see, the system builds up by itself. The only thing you need is good seeding. After that, it extends in "50 meters chunks" (the range of a newly found wifi connection).
Of course, if you really want the system go banana, you can start exchanging wifi routers around the globe with fellow revolutionaries of the no-global-positioning movement.
They use a combination of IP geolocation, as well as comparing the results of a scan for nearby wireless networks with a database on their side (which is built by collecting GPS coordinates alongside wifi scan data when Android phone users use their GPS)
It's a lot more simple that you think. You've signed into both your mobile and Chrome on your desktop using the same Google account. Google simply expect you will have your mobile with you most of the time. They take the location data from your phone and assume the location of your current desktop session is the same.
I proved this by RDPing into my Windows machine at home from work and checking Google maps remotely. It show my location as the same as Chrome on Linux at work.
If you don't have a mobile that is signed into Google then all they can do is lookup GeoIP data for the IP address assigned by your ISP. It will typically be wildly inaccurate.
I've finally worked it out. The biggest issue is how they managed to work out what Wireless networks were around me and how do they know where these networks are.
It "seems" to be something similar to this:
- skyhookwireless.com [or similar] Company has mapped the location of many wireless access points, i assume by similar means that google streetview went around and picked up all the photos.
- Using Google gears and my browser, we can report which wireless networks i see and have around me
- Compare these wireless points to their geolocation and triangulate my position.
Reference: Slashdot