[Gdal-dev] warping a file from state plane to GD using gdal 1.3.2

[Derrick Hoffman]

All:

I have a geo Tiff that is in state plane and I want to warp it to
geodetic.  When I perform a GDAL info on the source file, the datum is
unknown.  I can sue the same file with FW Tools and the datum does come
across and the file can be warped.  Is there any reason why the base
gdal cannot read this information from the file?

Thanks :)


Derrick Hoffman
Software Engineer
Pro Logic Inc.
Fairmont, WV
(304) 333-2680 x 322

-----Original Message-----
From: gdal-dev-bounces at lists.maptools.org
[mailto:gdal-dev-bounces at lists.maptools.org] On Behalf Of Frank
Warmerdam
Sent: Monday, December 11, 2006 2:06 AM
To: Martin.Spott at mgras.net
Cc: gdal-dev at lists.maptools.org
Subject: Re: [Gdal-dev] ogr2ogr Default Output SRS

Martin Spott wrote:
> Frank,
> 
>> However, the solution, I think would be for OGR to:
> [...]
>>   o Provide a mechanism (a layer creation option for instance) so
>>     that the user can force use of a particular SRID whether OGR
>>     thinks the coordinate systems match or not.
> 
> Sounds good - well, I thought that
> 
>   # ~> ogr2ogr [...] -t_srs 'EPSG:4326
> 
> does this already !?


Martin,

The -t_srs switch causes EPSG:4326 to be expanded into a full well
known text representation.  It is that well known text representation
that is searched for in spatial_ref_sys.  I would also stress that SRID
is not the same as EPSG in general.  Though it just happens that the
SRID
of all predefined spatial reference systems in postgis happens to have
matching values with the EPSG ids.  But that doesn't mean they are
always
a 1:1 mapping.

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

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