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I'm trying to use a map of Austrias districts from the GADM project. The Shapefile can be found here: AUT_adm.zip (All other formats provided by the project appear exectly equal.)

The coordinate reference system is latitude/longitude and the WGS84 datum.

Comparing this map with the official (but not as detailed) NUTS3 shapefiles from "Statistics Austria" and with Google Maps (all done within QGis) shows differences between the borders of the administrative areas.

Google Maps (and OpenStreetMap, ...) are nearly equivalent with the files from Statistics Austria. Unfortunately, the maps from GADM are not congruent with the other sources. Additionally the distortion grows from West to East.

West of Austria (GADM=red, StatA=green, Google maps as reference): GADM, StatA and Google Maps

East of Austria (GADM=red, StatA=green, Google maps as reference): enter image description here

Of course I tried to import the original data as well as projections to the same CRS (epsg:3857). As expected this did not alter the results.

My questions:

  • Am I using a wrong projection for the GADM data? (Is the documentation on the homepage and the files not corret.)
  • How can I get the right projection and get rid of the differences?
  • Whenever I acquire data from GADM through R it always ships in WGS84 projection... – Curlew Sep 5 '14 at 11:58
  • I'm also using WGS84 projection (which is also stored in the shapefile and provided R objects). To be precise, I'm using EPSG:4326 for the GADM data. Nevertheless, the presented differences occure... Are you able to get a precise match between GADM and Google Maps or the linked NUTS3 data respectively? – FloE Sep 5 '14 at 12:30
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I agree that the data is offsetted, but it is not a constant offset. I compared it with Openstreetmap boundaries from https://osm.wno-edv-service.de/boundaries/ in blue:

enter image description here

The Vienna borders are off to the North, but the state border to the east is almost correct. So there is not much more that you can do with the data than delete it. Take the borders from OSM from the source above, they are pretty accurate by now.

  • Thanks! I didn't know this service. Is there any chance to get the boundaries from the year 2007? Some things changed since then... – FloE Sep 5 '14 at 15:48
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    I'm afraid not. OSM exists since 2004, but I guess there was not much data in there at the time. At least not as accurate as today. – AndreJ Sep 5 '14 at 18:17

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