Trying to figure out epsg for a GeoTIFF

[Frank Warmerdam]

Dennis Megarry wrote:
> I'm going to sound like as complete newbie be assking this (which I am
> really).
> 
> I have a GeoTIFF raster image and I'm not sure how to setup the projection
> in my map file.  Can someone take a look at the below info from gdalinfo
> and tell me what I need to do?  If at all possible, some details so I can
> learn a bit?
> 
> Driver: GTiff/GeoTIFF
> Size is 11873, 8123
> Coordinate System is:
> PROJCS["unnamed",
>     GEOGCS["NAD83",
>         DATUM["North_American_Datum_1983",
>             SPHEROID["GRS 1980",6378137,298.2572221010042,
>                 AUTHORITY["EPSG","7019"]],
>             AUTHORITY["EPSG","6269"]],
>         PRIMEM["Greenwich",0],
>         UNIT["degree (supplier to define
> representation)",0.01745329251994328],
>         AUTHORITY["EPSG","4269"]],
>     PROJECTION["Lambert_Conformal_Conic_2SP"],
>     PARAMETER["standard_parallel_1",38.6666666666667],
>     PARAMETER["standard_parallel_2",33.33333333333337],
>     PARAMETER["latitude_of_origin",0],
>     PARAMETER["central_meridian",-81.45000000000009],
>     PARAMETER["false_easting",0],
>     PARAMETER["false_northing",0],
>     UNIT["metre",1,
>         AUTHORITY["EPSG","9001"]]]

Dennis,

This translates into PROJ.4 format as:

PROJECTION
   "+proj=lcc +lat_1=38.6666666666667 +lat_2=33.33333333333337 +lat_0=0 
+lon_0=-81.45000000000009 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m 
+no_defs"
END

You can find some useful information on how to express projections
in PROJ.4 format at:

   http://geotiff.maptools.org/proj_list

The libgeotiff listgeo utility can also report PROJ.4 format
with the -proj4 switch.

But I did this by saving the WKT (ie. PROJCS[...]) into a text
file, and running the gdal/ogr/testepsg utility against it.
Testepsg is an undocumented GDAL utility not built by default.

One day I must really provide a supported utility for doing these
sorts of translations.

Best regards,

-- 
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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    | Geospatial Programmer for Rent