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Currently I am working on a project with QGIS (2.14.1). Therefore I need to add old (but important) shapes that were drawn by a colleague.

Somehow most of the .prj-files are missing - I don't know why, maybe they were deleted by accident or not created at all. Those shapes with mising prj meta-data are not displayed correctly, depending on the CRS I choose for them they eather appear on a random place on earth or are not displayed at all.

I don't have a clue what I can do, is it even possible to fix that somehow? Maybe via reprojection or something?

I don't know the original projection btw.


The project area covers parts of Southwestern-Germany, County of Rhineland Palatinate, close to Mainz. Based on that I created prj files via spacialreference.org for potential CRS (eg. EPSG 31466, 31467, 3044, 31493, 3857, 32632). Unfortunately without success.


Layer extent: xMin,yMin 3430186.73;5517809.87 : xMax,yMax 3443672.61;5529390.81

  • If you know which projection it is by code you can use spatialreference.org/ref/epsg/4326 and get the .prj file from the ".prj File" link. Save by using the same base name as the .shp part. – user30184 Apr 19 '16 at 10:11
  • If you do not know the original projection you have only two alternatives: Ask from someone who knows (data provider, your colleague) or guess. – user30184 Apr 19 '16 at 10:48
  • Is there ANY metadata that might hint at which projection was used. Which country, which software,what purpose, when was the data created, what was the purpose. Do the original project files exist. have you tried ogrinfo on the shapes (will tell you whether you have degrees or meters/feet as units) – nmtoken Apr 19 '16 at 11:46
  • Please edit your question with the extent of the shapefile and what location it represents (city, county, or administrative district, etc.). Someone may be able to help you identify it using AndreJ answer. – mkennedy Apr 19 '16 at 13:34
  • Thanks. I've added the location. Also i testet different projections without success. Guess I will have to redraw the shapes manually. – Vogon_Jeltz Apr 22 '16 at 7:29
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If the shapefiles were created with QGIS, you could look into the .qgs file with a text editor.

Otherwise, you can run ogrinfo -al -so filename to get the extent of the data.

If it is between +/- 180/90, you can take EPSG:4326 as first chance; else it is a projected CRS.

If you can identify a point (x;y) from the shapefile in Google Maps or other reference basemap with (longitude;latitude), you can set up a custom transverse mercator projection on that point with:

+proj=tmerc +lat_0=(latitude) +lon_0=(longitude) +k=1 +x_0=(x) +y_0=(y) +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs

From the origin of that projection you might guess the center of the projection used by your colleague.

You might as well query http://georepository.com/search/map, http://projfinder.com/ or http://epsg.io/ for projections used in your study area.


UPDATE

from the region and extent you added, my first guess would be DHDN Gauss-Krueger zone 3 EPSG:31467, and it seems to fit:

enter image description here

If you encounter a shift of about 100m, the datum shift from Potsdam datum to WGS84 is missing on your side, or your colleagues data. ESRI shapefiles usually have not stored the shift inside the file.

  • Or how about the original registry where a lot (most) of the data at the other sites pulled their information. Disclosure: I help maintain the original registry (EPSG Geodetic Parameter Registry). – mkennedy Apr 19 '16 at 13:32
  • I have used the EPSG: 31467 on all of the 50 incomplete shapefiles and it is working! Kudos and big thanks! Redrawing them by hand would have been a work of many days. – Vogon_Jeltz Apr 22 '16 at 9:50
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When you know the original coordinate system you just can copy and rename existing prj files. But I guess that is the problem.

  • Thanks, unfortunately I don't know the original projection. I tried to guess several projections and created the prj files with spatialreference.org as advised but they didn't match :-/ – Vogon_Jeltz Apr 19 '16 at 10:21

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