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I got a dataset of Hamburg, Germany in so called "Lagestatus 320" (LS320). The metadata describes it as "Gauss-Krueger mit ETRS89 [Lagestatus 320]". Coordinates are like 3565575.3,5936627.0, they are metric.

The epsg database does not have such a coordinate reference system. The closest option is EPSG:31467 aka "DHDN / 3-degree Gauss-Kruger zone 3". Of course, this uses the wrong ellipsoid.

If I assign that to my data, things end up ~600 meters north of their proper location.

How can I properly use this data in QGIS or any other proj-based software?

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You have to create your own custom CRS using the correct ellipsoid.

DHDN projections use +ellps=bessel +towgs84=598.1,73.7,418.2,0.202,0.045,-2.455,6.7.

ETRS89 projections use +ellps=GRS80 +towgs84=0,0,0,0,0,0,0.

The full proj string for EPSG:31467 is:

+proj=tmerc +lat_0=0 +lon_0=9 +k=1 +x_0=3500000 +y_0=0
+ellps=bessel +towgs84=598.1,73.7,418.2,0.202,0.045,-2.455,6.7
+units=m +no_defs

So switch the ellipsoid stuff for the ETRS89 parameters like this:

+proj=tmerc +lat_0=0 +lon_0=9 +k=1 +x_0=3500000 +y_0=0
+ellps=GRS80 +towgs84=0,0,0,0,0,0,0
+units=m +no_defs
  • For the record: I am not sure if the +towgs84 line is correct like that. It works for me but maybe someone could share some insight. GRS80 was the same as WGS84 but according to Wikipedia WGS84 changed slightly? en.wikipedia.org/wiki/GRS_80 – bugmenot123 Aug 24 '16 at 11:33
  • You can find a point raster with coordinates in GK and UTM as WFS, XML and TXT at govdata.de/apps/-/details/virtuelle-passpunkte-hamburg – AndreJ Aug 24 '16 at 14:09
  • How do I use that (with free software) and does it improve accuracy compared to my solution? – bugmenot123 Aug 24 '16 at 14:12
  • You can put sample UTM coordinates in a text file and run cs2cs on it: cs2cs +init=epsg:5652 +to +proj=tmerc +lat_0=0 +lon_0=9 +k=1 +x_0=3500000 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs -f "%%.3f"<HH-in.txt >>HH-out.txt Accuracy is below 1mm to the GK coordinates in the TXT file, so your parameters seem to be correct. – AndreJ Aug 24 '16 at 14:36
  • Ah, you mean I can use it for validation? Thanks for the suggestion and trying it already! – bugmenot123 Aug 24 '16 at 15:27

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