[Gdal-dev] NAD83 Fipszone 903 to WGS84 Error

[Frank Warmerdam]

On Tue, 4 Jan 2005 16:30:16 +0000 (UTC), Eric Lindahl <eric at 21csi.com> wrote:
> 
> Hi,
> 
> I attempted to fix the PRJ.ADF import that didn't recognize the FIPSZONE
> key word.
> 
> 691,692c694,704
>          int nZone = (int) OSR_GDV( papszPrj, "zone", 0.0 );
>          nZone = ESRIToUSGSZone( nZone );
> ---
>          double def = -10000.0;
>          double dZone = OSR_GDV( papszPrj, "zone", def );
>          int nZone = 0;
>          if( dZone == def ){
>            dZone = OSR_GDV( papszPrj, "Fipszone", def );
>            nZone = (dZone==def)?0:(int)dZone;
>          }else{
>            nZone = (int)dZone;
>            nZone = ESRIToUSGSZone( nZone );
>          }

Eric,

The above looks like a useful patch.  Could I get the .prj file in question for
my "sample file collection" and so I can test things out?

> Coordinate System is:
> PROJCS["NAD83 / Florida North",
>     GEOGCS["NAD83",
>         DATUM["North_American_Datum_1983",
>             SPHEROID["GRS 1980",6378137,298.257222101,
>                 AUTHORITY["EPSG","7019"]],
>             AUTHORITY["EPSG","6269"]],
>         PRIMEM["Greenwich",0,
>             AUTHORITY["EPSG","8901"]],
>         UNIT["degree (supplier to define representation)",0.01745329251994328,
>             AUTHORITY["EPSG","9122"]],
>         AUTHORITY["EPSG","4269"]],
>     PROJECTION["Lambert_Conformal_Conic_2SP"],
>     PARAMETER["standard_parallel_1",30.75],
>     PARAMETER["standard_parallel_2",29.58333333333333],
>     PARAMETER["latitude_of_origin",29],
>     PARAMETER["central_meridian",-84.5],
>     PARAMETER["false_easting",600000],
>     PARAMETER["false_northing",0],
>     UNIT["Foot (International)",0.3048],
>     AUTHORITY["EPSG","26960"]]

It looks like my code in ogr_srs_esri.cpp for morphing the units
of the SRS is screwed up.  The 600000 meter false easting 
should have been converted from meters to feet when the linear
units were changed to feet.  But instead it looks like the conversion
was done the wrong way.   Also, I really need to clear the
AUTHORITY keyword if I change the units. 

Apparently the units changing code is *not* well tested in the ESRI
projections support code.  In any event, once I have the .prj file 
in question I can engineer in a solution to this. 

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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