[gdal-dev] Shapefile to Lambert Azimuthal Equal Area

[Frank Warmerdam]

Kent Eschenberg wrote:
> Any idea why I cannot convert a shapefile to the Lambert azimuthal equal 
> area projection? I tried
> 
> ogr2ogr -t_srs EPSG:9820 -f "ESRI Shapefile" destination.shp source.shp
> 
> and saw the message
> 
> ERROR 6:
> EPSG PCS/GCS code 9820 not found in EPSG support files.  Is this a valid
> EPSG coordinate system?
> Failed to process SRS definition: EPSG:9820
> 
> I'm using GDAL 1.4.2 on Fedora core 6.

Kent,

EPSG 9820 is the identity of a projection method (ie. algorithm), but
to use it you also need to know the parameters to the algorithm (things
like central meridian, false easting, scale).  If you want to specify
things by EPSG code you would need to find a projected coordinate system
using LAEA and use that PCS's code.

What coordinate system do you want?

If you want to use LAEA with custom parameters, you can define it using
PROJ.4 format, or a WKT file.  In WKT you might use something like:

PROJCS["unnamed",
     GEOGCS["WGS 84",
         DATUM["WGS_1984",
             SPHEROID["WGS 84",6378137,298.257223563],
             TOWGS84[0,0,0,0,0,0,0]],
         PRIMEM["Greenwich",0],
         UNIT["degree",0.0174532925199433]],
     PROJECTION["Lambert_Azimuthal_Equal_Area"],
     PARAMETER["latitude_of_center",0],
     PARAMETER["longitude_of_center",0],
     PARAMETER["false_easting",0],
     PARAMETER["false_northing",0]]

Or in PROJ.4:

    +proj=laea +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org