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I would like to know whether it is possible to convert the coordinates given in a NAV4 coordinates system into WGS84. I could not find out what NAV4 is and if it is actually a standardized CRS.

Here is an excerpt from the XML document which contains the coordinates:

<stop stopID="2309" name="Rasthaus" locality="Unterwittelsbach">
  <place selected="0">
    <placeID>36</placeID>
    <placeName>Unterwittelsbach</placeName>
    <OMC>9771113</OMC>
  </place>
  <coords>
    <coordSystem>NAV4</coordSystem>
    <longitude>4437685</longitude>
    <latitude>788825</latitude>
  </coords>
</stop>

Is there a EPSG reference which uniquely identifies NAV4? I could not see any helpful information in the document which help to identify the CRS used.

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What program produced that XML? –  R.K. Nov 10 '12 at 15:50
    
It is the output of the public transport information system (EFA). I am trying to reverse engineer the coordinates and cannot tell anything more about the source. –  JJD Nov 11 '12 at 2:06
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1 Answer 1

On second though, it seems to be UTM Zone 32 (EPSG 32632).

Your coordinates

<longitude>4437685</longitude>
<latitude>788825</latitude>

seem to fit within the projected bounds.

166021.4431  833978.5569, 

0.0000      9329005.1825

You might also want to try check UTM Zone 33 (EPSG 32633). Try plotting them and see if they fall in the right locations. Once you're sure, you can use Proj4 or some other cartographic projections library to convert it to WGS84.


Just checked the places and they all seem to be in Bavaria. You might want to check if those coordinates are Gauss Kruger Zone 4. It's EPSG 31468 if I'm not mistaken.

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Could you please describe the process how exactly you find out about the projection being used so I can apply the method to other data sets? Are the bounds the only thing you check for? –  JJD Nov 11 '12 at 19:59
    
I considered the places in the XML file and where the file was produced. I then checked what projections are currently used in those areas. Since the data is from Germany, I did some research and found that two projection groups are used there: UTM and Gauss Kruger. It was then a matter of checking the bounds and looking at the coordinates. Did I get it right? –  R.K. Nov 12 '12 at 3:33
    
Thank you. That means, there is no way to automate this process completely? –  JJD Nov 12 '12 at 20:43
    
I don't know. Maybe somebody here knows. Best to ask it in a separate question. –  R.K. Nov 13 '12 at 2:27
    
Or I could add the attribute "automatically" to my question title? –  JJD Nov 13 '12 at 20:10
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