[Proj] Re: SRS stuff broken in GDAL and PROJ

Frank Warmerdam warmerdam at pobox.com
Thu Apr 24 14:59:50 EDT 2008

Maciej Sieczka wrote:
>> I believe these problems are due to a change in GDAL/OGR to use CPLAtof()
>> which gives slightly different results than atof() in some cases.
>>   http://trac.osgeo.org/gdal/ticket/2036
> Ouch. So SRS stuff is pretty much broken in GDAL and PROJ. I subscribed 
> to the ticket and I'd be happy to help with testing.


I disagree with the assessment that things are broken.  They are just
a little bent. Numerically the differences are insignificant.  The
issue is with comparing string representations of coordinate systems.

>> Perhaps you could work with Andrey on this problem and then I could
>> regenerate things.
> Please do. Can you say what is the latest safe GDAL version? As for PROJ 
> - is it necessary to revert to 4.5.0 or is copying the epsg file from 
> 4.5.0 to 4.6.0 installation enough?

Generally using the older epsg file is sufficient.

>> BTW, we use a custom CPLAtof() so that coordinate systems with non "C"
>> locale numbers can be parsed, and so that "C" locale numbers can be
>> parsed in non "C" locales.
> If that's not too much offtopic, can you explain why GDAL/OGR supports 
> non-C locale numbers in SRS stuff? I never saw an SRS definition with 
> comma instead of dot as a decimal separator (though I've been living in 
> a non-C country). Are they common?

They are not common, but they do occur and I was asked to make them work.

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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