[Qgis-developer] ED50 datum

[Frank Warmerdam]

On Tue, Sep 7, 2010 at 5:08 AM, Paolo Cavallini <cavallini at faunalia.it> wrote:
> Hi all.
> The EPSG def for ED50 (EPSG:23032) is a standard one:
> +proj=utm +zone=32 +ellps=intl +units=m +no_defs
> For Western Europe, the corrected datum is:
> +proj=utm +zone=32 +ellps=intl +units=m +no_defs +towgs84=-87,-96,-120,0,0,0,0
> Any objection to add it, as we have done for 3003 etc.?
> All the best.

Paolo,

I would note that the EPSG init file now (perhaps only in trunk,
not the release) has:

# ED50
<4230> +proj=longlat +ellps=intl +towgs84=-87,-98,-121,0,0,0,0 +no_defs  <>

For some reason, this EPSG derived towgs84 value is slightly
different than the one you propose.  I would like to encourage
the QGIS team to work with me to ensure that such adjustments
are not done differently in QGIS than in the upstream database.

I will note that a substantial overhaul was done over the last year
to incorporate better datum shift selection when converting the
EPSG database to a proj.4 init file.

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