Geolocation

HTML 5 geolocation

Kristoffer Snabb

Scope of the working group

• Retrieve a users location only once• Retrieve several data points over time• Retrieve a sequence of locations at irregular

intervals (e.g. each time a photo is taken)

Geolocation API

• Simple interface to get user location with the help of three functions– getCurrentPosition– watchPosition– clearWatch

The interface

• navigator.geolocation.<function name>• successCallback, errorCallback• PositionOptions– enableHighAccuracy – False, True– Timeout– maximumAge– requireCoords – True, False– requestAddress – False, True

The output

• Coords– latitude, longitude, altitude, accuracy,

altitudeAccuracy, heading, speed, verticalSpeed• Address– country, region, county, city, street, streetNumber,

premises, postalCode• timestamp

What makes it complex?

Triangulation/forward link examples

• GPS– Accuracy about 10m– Does not work indoors

• Wi-Fi– Accuracy about 20m– Works indoors

• Cell tower– Accuracy depends on cell coverage

Geo IP example

• Mobile phone ip address is ephemeral?• Latency and traceroute information

Social network example

• likelihood of friendship with a person is decreasing with distance

• Your friend shared location with GPS• Your friends profile has an address Good enough for marketing, good computational performance and increased location probability when used with geo IP

Search query analysis example

References

• Spatial variation in search engine queries, www2008, L. Backstrom, J. Kleinberg, R. Kumar, J. Novak

• Find me if you can: improving geographical prediction with social and spatial proximity, www2010, L. Backstrom, E. Sun, C. Marlow,

• Uses of W3C’s geolocation API, CINTI 2010, B. Pejic, A. Pejic, Z. Covic

• The locative Web, locweb2008, E. Wilde, M. Kofahl