[Gdal-dev] Needs help for reprojecting a shapefile with ogr2ogr

[Yves Jacolin]

Hi,

Your s_srs is incorrect, try :
ogr2ogr -f "ESRI Shapefile" -s_srs "EPSG:27582"  -t_srs "+proj=longlat +nodefs 
+datum=WGS84 +towgs84=168,60,-320" wgs dep_france_dom.shp

Regards,

Y.
Le Vendredi 8 Décembre 2006 16:47, Jean-Claude Repetto a écrit :
> Hello,
>
> 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).
>
> I am trying to convert the shapefile with ogr2ogr, but the result is wrong.
>
> 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).
>
> ogr2ogr -f "ESRI Shapefile" -s_srs "+proj=lcc +no_defs +lat_1=46.8
> +lon_0=0 +k_0=0.99987742 +x_0=600000 +y_0=2200000 +ellps=clrk80
> +pm=paris"  -t_srs "+proj=longlat +nodefs +datum=WGS84
> +towgs84=168,60,-320" 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 gives :
> long = 6.468923293704749,   lat = -0.979340169729739, which is obviously
> wrong.
>
> cs2cs gives the correct result :
> echo "801150 2092615" | cs2cs -f "%15.10f" +proj=lcc +no_defs
> +lat_1=46.8000 +lon_0=0 +k_0=0.99987742 +x_0=600000 +y_0=2200000
> +ellps=clrk80 +pm=paris +to +proj=longlat +datum=WGS84 +towgs84=168,60,-320
>     4.9245201351   45.8040401819   41.9436330358
>
>
> Am I doing something wrong, or is there a bug in GDAL 1.3.2 ?
>
>
> For more information about the projection parameters, you can look at :
> <http://www.remotesensing.org/geotiff/proj_list/lambert_conic_conformal_1sp
>.html> and
> <http://www.ign.fr/telechargement/MPro/geodesie/CIRCE/transfo.pdf>, page
> 12.
>
> Thanks for your help,
> Jean-Claude
>
>
>
>
>
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-- 
Yves Jacolin
---
http://yjacolin.gloobe.org