[gdal-dev] Geocentric 9603

[Frank Warmerdam]

On 11-05-06 09:48 AM, Luca Sigfrido Percich wrote:
>> I use the '-s_srs' command and when I overlay the shapefile over a
>> map,the adjustment isn´t very good with the map, so I must make a
>> geographic transformation. I get that transformation thanks to
>> 'ProjectionUtility' (ArcView). Its name is Geocentric[9603],
>> ED_1950_TO_WGS_1984_13, POSC Code:8045.
>>
>> I need to make this transformation automatically. How can I make this
>> transformation using 'ogr2ogr'? Is it possible?
>
> I'm just guessing 'cause I've never tried this. Check if ProjectUtility
> writes a .prj file; it should contain a WKT definition of the resulting
> dataset SRS. According to ogr2ogr doc, this WKT (or the name of the file
> containing it) can be passed to -t_srs or -a_srs.

Sig / Mario,

ESRI .prj files do not normally have the details of the datum shift
parameters in them.  I see the "stock" ED50 transformation in EPSG is
TOWGS84[-130,29,364,0,0,0,0] so hopefully you could do something like:

  ogr2ogr -s_srs "+proj=latlong +ellpse=clrk80 towgs84=-130,29,364,0,0,0,0" \
          -t_srs "+proj=latlong +datum=WGS84" \
          out.shp in.shp

or something similar.  This is assuming the coordinates are geographic
(lat/long), not projected.  If they are projected you will need a more
complex source and destination coordinate system description.

Best regards,
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