[GIS] GeoJson based on shapefile : large coordinates

coordinate systemgeojsonogr2ogrshapefile

I'm quite new to GeoJson (for use with d3), and in need of some help. When I convert my available shapefile (.shp) with ogr2ogr to a GeoJson-file, the resulting coordinates are very big numbers (in the range of 100000.000).

The shapefile is accompanied by a .prj file which states the following :

PROJCS["PCS_CarMAGBOG",GEOGCS["GCS_CarMAGBOG",DATUM["CGS_CarMAGBOG",SPHEROID["GRS80 Mod",6380687.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",92334.879],PARAMETER["False_Northing",109320.965],PARAMETER["Central_Meridian",-74.14659167],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",4.680486111],UNIT["Meter",1.0]]

How do I reverse-engineer this in order to get true latitude and longitude ?

Best Answer

You do not need any reverse engineering. ogr2ogr is able to read the projection information from prj file for you.

Just execute:

ogr2ogr -t_srs EPSG:4326 -f geoJSON -lco COORDINATE_PRECISION=7 future.geojson your_shapefile.shp

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QGIS Shapefile – Why Is My .prj File Not Being Read by QGIS?

The shapefile format consists of several (at least 3) computer files. To load a shapefile into QGIS you point to only the *.shp. The others are read automatically. QGIS does use the *.prj to determine the coordinate system of the data. From the *.prj you quoted above it seems to be in the coordinate reference system EPSG:27700. Here's the spatialreference.og link to a descriptiojn of that CRS.

Now you should be able to enable "On-the-Fly" reprojection and show this layer in any CRS you choose, such as 4326, as you already did. Why do you think the longitude is wrong?

[GIS] QGIS 1.8.0 – Define shapefile as UTM 15 NAD83 Feet

UTM is always in metres, being internationally standardized. The proj string for UTM 15N is:

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So if your data is in feet, create a custom CRS with this string:

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