Thursday, November 29, 2007

Geotagging district articles

In January this year I noticed that Google Earth started to include a new layer with Wikipedia articles. Though there were earlier activities like the layer created by Stefan Kühn, once there was an official layer it made it much more interesting to have all the district articles also listed in Google Earth, hopefully to attract more contributors adding informations. With the Google Earth FAQ it was then quite easy to make sure the article showed up, so the only work left to be done was to add the coordinates to all those articles.

For extended entities it is of course the difficult question of what single coordinate point to use to represent it. One might choose someplace in the "middle" of the district, but then it would usually point to a non-populated forest or farm area. But as traffic signs in Thailand point to the districts, and in fact point to the district offices, these IMHO make a good distinctive point representing the whole area.

My main source of the coordinates was an overlay I found at thaigoogleearth which includes the locations of all the district offices, and for those areas high resolution imaginary is available I confirmed and fine-tuned these locations, as they were sometimes a little bit off. The holes in the high-res coverage of Google Earth were filled with PointAsia, a similar software but having high-res coverage of almost all Thailand - but sensitive areas like military places or the palace of the King are blurred out. Sadly while I was adding the coordinates for the three southernmost provinces Pattani, Yala and Narathiwat suddenly the high-res images in PointAsia disappeared. Maybe they worried they get used by the terrorists struggling these provinces, but I doubt it would hinder them a bit, as they are probably locals who know the places well enough without the need to use online satellite imaginary.

But with the help of the MapMagic map, and the street maps of Google Maps, now all districts have their geotag at least pointing close to the district office, and all show up in GoogleEarth already - except Wiang Kao created in 2005, which I could not find in any of the sources. All I know is that it is somewhere in the subdistrict Nai Mueang, but no more details yet.

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