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

Frank Warmerdam warmerdam at pobox.com
Mon May 5 14:57:02 EDT 2008

Maciej Sieczka wrote:
> Out of the 2865 common EPSG codes, proj4 strings of 133 of them are
> different enough between the epsg files of PROJ 4.5 and 4.6 to result in
> re-projection errors of few centimeters most of the time, about a meter
> in several cases to as much as kilometers in few. I would call this a
> critical issue.


I am presuming that the ones with large differences are due to the fact
that PROJ 4.6.0 does *not* apply a change-of-ellipse shift when no
datum to wgs84 mapping information is available.

I would suggest you isolate 2-3 examples out of your list that you are
confident are significant issues and we can discuss them in more detail.
Please ensure that you have worked out whether the significant difference
is in the PROJ.4 string generated for the epsg file, or whether it is
the behavior of PROJ.4 between 4.5 and 4.6 that you think is responsible.

It is important to isolate particular issues and try to understand them

As you likely know Andrey has committed a fix in the last day or two
for CPLAtof() and with this change we should be able to generate an
epsg init file without the slight round off differences.

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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