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I have a series of points around the greater london area (may be also around 100-200kms away from it) like those here in the format Lon, Lat:

43032.1,32681
95816.5,34473.8
15439.3,-13987

The Application to which those points are transferred uses leaflet but does not use any of EPSG3857, EPSG4326, EPSG3395 from http://leafletjs.com/reference.html unfortunately. At least that's what I found out when using the proj cmdline tool like this:

echo -48884.4 64535.7 | cs2cs -f "%.10f" +init=epsg:3395 +to +init=epsg:4326

I really tried a lot of possible projections and flipped the order but I cannot find a way to get a plausible result which should be something like 51.xxxx -0.1xxxxx

Does someone have any idea on what projection may be used here?

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  • can you show where one of those points is supposed to be ?
    – radouxju
    Mar 26, 2015 at 10:51
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    @radouxju 13716.1,975.7 is at -0.33038,51.47847 EPSG4326 Mar 26, 2015 at 11:44
  • Those coordinates look to me like meters not degrees (long, lat). Degree values usually lie in the range -180 to +180.
    – nmtoken
    Mar 27, 2015 at 9:20
  • @nmtoken I took the labels lon and lat from the webapp, It could be as you say they don't make sense Mar 29, 2015 at 8:47

1 Answer 1

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I'm not sure if this will help in your case, but this online tool may be worth a try. If you can create a shapefile of the points, this tool will attempt to guess the projection.

From Projection Guesser:

One of the joys of map making is getting a shapefile without a projection. We eventually decided to stop doing those puzzles manually and wrote something that harnesses the power of PostGIS to try every single projection in its database.

Steps

  1. Zip your .shp + .shx (you don't need the .dbf)
  2. Drag the .zip onto the map.
  3. Wait.
  4. Click on the shape that looks correct
  5. Click on the .prj link
  6. Save the contents of that page to your .prj file

It says it works best with single polygons; don't know if it will work on points.

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  • It's no longer online, but you can download and run it if you have PostGIS. Nov 16, 2018 at 0:01

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