I have downloaded a shapefile of France (freely available from the IGN website at http://www.ign.fr/telechargement/MPro/produit/GEOFLA_Dep/GEOFLA-dep-L2-SF.ZIP .
The shapefile contains data in tangent Lambert Conic Conformal projection, but I need geographical coordinates (longitudes, latitudes).
Since the projection and CS informations are not included in the original files, I have used the s_srs option to specify them (the tangent Lambert Conic Conformal projection (lcc1) and the NTF system).
When I use the EPSG code (27572), the result is correct :
ogr2ogr -f "ESRI Shapefile" -s_srs "EPSG:27572" -t_srs "+proj=longlat +nodefs
+datum=WGS84" wgs dep_france_dom.shp
The coordinates of the first point of the original file are :
X=801150 Y=2092615
The result of the ogr2ogr command is :
4.924520108855378 45.804040002011874, which is correct.
Then I translate the EPSG code to PROJ.4 format:
$ epsg_tr.py -proj4 27572
# NTF (Paris) / Lambert zone II
<27572> +proj=lcc +lat_1=46.8 +lat_0=46.8 +lon_0=0 +k_0=0.99987742 +x_0=600000 +y_0=2200000 +a=6378249.2 +b=6356515 +towgs84=-168,-60,320,0,0,0,0 +pm=paris +units=m +no_defs <>
and I type this command :
$ ogr2ogr -f "ESRI Shapefile" -s_srs "+proj=lcc +lat_1=46.8 +lat_0=46.8 +lon_0=0 +k_0=0.99987742 +x_0=600000 +y_0=2200000 +a=6378249.2 +b=6356515 +towgs84=-168,-60,320,0,0,0,0 +pm=paris +units=m +no_defs" -t_srs "+proj=longlat +nodefs
+datum=WGS84" wgs dep_france_dom.shp
Now, the result is :
7.261840271142879 45.804051007612635, which is wrong.
