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I have a data file exported from an ARCGIS system (parcel data from local government). Its a zip file containing 7 files: f.dbf, f.prj, f.sbn, f.sbx, f.shp, f.shp.xml, f.shx.

I have a simple ruby script that uses the rgeo and rgeo/shapefile gem to read the .shp file and extract points. The points don't look like lat, long eg.

936934.017177403 695547.1331697404 

I would like to convert the points to lat longs that I can upload to google maps or similar.

I think the solution involves reading the .prj and .shp file, then telling the tool to project into EPSG:3867.

Is there a simple script or commandline tool that handles conversions like this. eg:

convert f.shp f.prj -EPSG:3857 > new.shp

I would prefer to use a ruby / rgeo solution. But anything unixy that can be scripted would work.

  • Is this a polygon or point layer? – GISKid Jun 28 '16 at 22:40
  • There are 100K records, from what I can tell all MULTIPOLYGON. – Patrick Cullen Jun 28 '16 at 23:11
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That is a trivial task with gdal:

 ogr2ogr -t_srs EPSG:3857 destination.shp source.shp

See http://www.gdal.org/ogr2ogr.html for more information.

There might be ruby bindings for this, I have no idea.

EPSG:3857 coordinates are not lat/long though, if you really need those, just use EPSG:4326.

  • Does ogr2ogr reads the .prj file implicitly? – Patrick Cullen Jun 29 '16 at 17:55
  • The args are reversed, should be ogr2ogr -t_srs EPSG:3857 new.shp old.shp. – Patrick Cullen Jun 29 '16 at 17:58
  • Oops, fixed. Yes, for GDAL/OGR the .prj file is just part of the Shapefile. – bugmenot123 Jun 30 '16 at 11:08

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