Geocoding from 100 Feet Under

I stumbled upon this image posted by Ellie K. on Google+

The title is World map of Flickr and Twitter locations and the legend is that red dots are locations of Flickr pictures, blue dots are locations of Twitter tweets and white dots are locations that have been posted to both.

You may be able to see your city following this link.

For example Copenhagen looks like this:

Here you have Copenhagen in Denmark to the left and Malmoe in Sweden to the right.

The strip between is the fixed link known as the Øresund Bridge.

However the connection isn’t entirely a bridge. If you look at a flyover picture you may think that there wasn’t money enough to finish the connection. Fortunately there was. The part closest to Copenhagen Airport is a 4 kilometer (2.5 miles) undersea tunnel.

So what puzzles me is the dots apparently representing Flickr uploads and tweets made from the tunnel. Are you able to upload to Flickr from down there? How are the tweets geocoded with that precision? My GPS never works when passing the tunnel.

(PS: I know you may geotag when back to surface)

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2 thoughts on “Geocoding from 100 Feet Under

  1. Clarence Hempfield 9th September 2011 / 13:53

    Hi Henrik,

    While it is likely that some of those tweets and photos were geotagged before entering or after exiting the tunnel – as you indicate, it is also possible that a fair percentage of those were not “precisely” geocoded in the first place. Accuracy varies widely among some of the commercially available geocoding technologies.


    • Henrik Liliendahl Sørensen 10th September 2011 / 09:38

      Thanks Clarence. That’s true. I have however a feeling that many Flickr uploads has a manually attached geotag and that my Twitter is geocodeded as a central spot in Copenhagen.

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