[postgis-users] Transform not transforming longitude

[Frank Warmerdam]

Nathaniel wrote:
> Hello all,
> 
> I've recently installed PostGIS/Proj4/GEOS.
> 
> Calls to Transform() between two datums (Eg
> WGS84->NAD27, WGS84->ED50) are not altering the
> longitude. Also, the latitude change is not exactly
> right (compared to other reliable transformers).

Nathaniel,

I suspect the datum shift grid files for NAD27 were not installed.
Do you have files like /usr/local/share/proj/conus on your system?

By default the EPSG lookup file does not have datum shift parameters
for ED50.  So it will only do ellipsoid change (via Geocentric
transformations) if you do a default ED50 <-> WGS84.

Best regards,
-- 
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