[gdal-dev] could GDAL enforce towgs84=0, 0, 0 for ETRS89-based CRSs?

[Frank Warmerdam]

Maciej,

Please file a ticket against the PROJ trac on this issue.  I'm hoping to
take advantage of datum and other definitions from CSMap at some point
which may help.  Otherwise, I'll try and include an override for ETRS89
which indicates that it can be treated as equivelent to WGS84 if
that is in fact a reasonable approach.

Best regards,
FrankW

On Wed, Jul 30, 2008 at 6:01 PM, Maciej Sieczka <tutey at o2.pl> wrote:
> Hi,
>
> Due to a change in PROJ 4.6.0, no datum shift is aplied when
> reprojecting between a CRS which has an implicit datum definition (e.g.
> Pulkovo 1942/58-based EPSG 4179, for which GDAL uses
> towgs84=33.4,-146.6,-76.3,-0.359,-0.053,0.844,-0.84) and an ETRS89-based
> CRS, e.g. EPSG 2180, that has no implicit towgs84 or datum.
>
> The above results in reprojection errors of about 150 m and makes using
> EPSG codes for ETRS89-based CRS impossible. Could PROJ.4 and GDAL
> enforce towgs84=0,0,0 for all ETRS89 CRSs that have no implicit datum
> definition otherwise?
>
> For instance, GRASS always forces towgs84=0,0,0 for EPSG 2180 and does
> the reprojection right.
>
> Maciek
>
> --
> Maciej Sieczka
> www.sieczka.org
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>



-- 
---------------------------------------+--------------------------------------
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