[gdal-dev] Validating a projection

[Andre Joost]

Am 07.06.2015 um 18:50 schrieb Doug McCorkle:
> Hello,
>
> I am trying to add this projection to our runtime environment:
>
> PROJCS["USA_Contiguous_Albers_Equal_Area_Conic_USGS_version",
> GEOGCS["GCS_North_American_1983", DATUM["D_North_American_1983",
> SPHEROID["GRS_1980",6378137.0,298.257222101]],
> PRIMEM["Greenwich",0.0], UNIT["Degree",0.0174532925199433],
> AUTHORITY["EPSG","4269"]], PROJECTION["Albers_Conic_Equal_Area"],
> PARAMETER["False_Easting",0.0], PARAMETER["False_Northing",0.0],
> PARAMETER["Central_Meridian",-96.0],
> PARAMETER["Standard_Parallel_1",29.5],
> PARAMETER["Standard_Parallel_2",45.5],
> PARAMETER["Latitude_Of_Origin",23.0], UNIT["Meter",1.0],
> AUTHORITY["EPSG","102039”]]
>

>  When I try to validate the projection I get this in the debug
> output:
>
> OGRSpatialReference::Validate: PARAMETER Central_Meridian for
> PROJECTION Albers_Conic_Equal_Area is an alias for
> longitude_of_center.
>
> I am unsure of what to do with this debug information to correct the
> definition. This is the proj4 definition:
>
> # USA Contiguous Albers Equal Area Conic USGS version <102039>
> +proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23.0 +lon_0=-96 +x_0=0
> +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs <>
>

If you run gdalsrsinfo on this proj.4 string, you get the following WKT 
output:

PROJCS["unnamed",
     GEOGCS["NAD83",
         DATUM["North_American_Datum_1983",
             SPHEROID["GRS 1980",6378137,298.257222101,
                 AUTHORITY["EPSG","7019"]],
             TOWGS84[0,0,0,0,0,0,0],
             AUTHORITY["EPSG","6269"]],
         PRIMEM["Greenwich",0,
             AUTHORITY["EPSG","8901"]],
         UNIT["degree",0.0174532925199433,
             AUTHORITY["EPSG","9108"]],
         AUTHORITY["EPSG","4269"]],
     PROJECTION["Albers_Conic_Equal_Area"],
     PARAMETER["standard_parallel_1",29.5],
     PARAMETER["standard_parallel_2",45.5],
     PARAMETER["latitude_of_center",23],
     PARAMETER["longitude_of_center",-96],
     PARAMETER["false_easting",0],
     PARAMETER["false_northing",0],
     UNIT["Meter",1]]

So it is really a matter of naming the same parameter. Using 
longitude_of_center will make all GDAL-dependent software happy, while 
the Central_Meridian might be invoked by ESRI.

See also 
http://www.remotesensing.org/geotiff/proj_list/albers_equal_area_conic.html 
for the official OGC WKT parameter names.

HTH,
André Joost