[OSM-dev] Mapnik: Data format in world_boundaries.tar.bz2 ?

[Karl Newman]

On Nov 29, 2007 5:49 AM, Hakan Tandogan <hakan at gurkensalat.com> wrote:
>
> On Thu, November 29, 2007 14:35, Martijn van Oosterhout wrote:
> > On Nov 29, 2007 2:06 PM, Hakan Tandogan <hakan at gurkensalat.com> wrote:
> >
> >> I fetched the Mapnik world_boundaries because it seems to contain a few
> >>  national boundaries which are not contained in the WDB archives.
> >>
> >> I can open the shape files just fine, but I don't know what units the
> >> points are in, the coordinates are quite large, and I don't want to
> >> guess...
> >
> > Hrm, did it not come with a .prj with some text in it, that how the
> > projection information is usually conveyed.
>
> Ah, o.k., there is a .prj next to it...
>
> PROJCS
> [
>  "Mercator",
>  GEOGCS["GCS_WGS_1984",
>  DATUM["D_WGS_1984",
>  SPHEROID["WGS_1984",6378137,298.257223563]],
>  PRIMEM["Greenwich",0],
>  UNIT["Degree",0.017453292519943295]],
>  PROJECTION["Mercator"],
>  PARAMETER["standard_parallel_1",0],
>  PARAMETER["central_meridian",0],
>  PARAMETER["scale_factor",1],
>  PARAMETER["false_easting",0],
>  PARAMETER["false_northing",0],
>  UNIT["Meter",1]
> ]
>
> This was all on one line, I reformatted it a little bit.
>
> >> Point Point(X=-19948430.3286263,Y=11572187.9256366)
>
> Any idea or pointers how I can transform those points into lat/lon
> coordinates? A perl library would be perfect ;-)

You can use ogr2ogr from the GDAL tools (www.gdal.org) to reproject
it. I think the command is something like:

ogr2ogr -f "ESRI Shapefile" -t_srs WGS84 outdir infile.shp

Karl