fredag den 31. oktober 2008

The Shape of Alpha

Der bliver taget rigtig mange billeder nu om dage og rigtig mange af disse bliver geo tagget. At man vha. disse alene kan bestemme konturerne af kontinenter, land, byer og helt ned til nabolag ... det er ret utroligt. Nu om dage tages der formentlig flere billeder om dagen end der gjorde om året tidligere ... (Jeg gad vide hvor mange år man skal gå tilbage i tiden for at dette holder stik)

A LOT of photos are taken all time and many of those are being geo tagged. Apperently there are enough of those to make out contours of the continents, the countries, the cities and even the neighbourhoods ... quite amazing. I guess more photos are taken each and every day than were taken in a year earlier ... (Wonder how many years back we need to go looking).


We have a lot of geotagged photos

Almost ninety million, as I write this, and the numbers keep growing especially as nearly every new smart phone released to market has not only a camera but also the ability to capture location information with it.

For every geotagged photo we store up to six Where On Earth (WOE) IDs. These are unique numeric identifiers that correspond to the hierarchy of places where a photo was taken: the neighbourhood, the town, the county, and so on up to the continent. This process is usually referred to as reverse-geocoding.

Over time this got us wondering: If we plotted all the geotagged photos associated with a particular WOE ID, would we have enough data to generate a mostly accurate contour of that place? Not a perfect representation, perhaps, but something more fine-grained than a bounding box. It turns out we can.


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