[postgis-users] Projection problem

[Ralf Suhr]

Hi Jaime,

to get transformation with towgs84 parameter working you have to use wgs84 
ellipsoid. Transform from ETRS89 to wgs84 and second from wgs84 to ED50.

ST_Transform(ST_Transform( 25830_geom, 4326), 23030)

Gr
Ralf

Am Freitag 23 Juli 2010, 08:42:39 schrieb Jaime Fiers:
> Hello guys
> 
> I hava a "little" problem with Postgis projection.
> 
> I need get a reprojected view.  Original data layer is in SRS=25830 (ETRS89
> UTM30) and view in SRS=23030 (ED50 UTM30)
> 
> I try this:
> 
> CREATE OR REPLACE VIEW vista_23030 AS
>  SELECT id, transform_geometry("GEOMETRY", '+proj=utm +zone=30 +ellps=GRS80
> +units=m +no_defs
> +towgs84=131.0,100.3,163.4,1.2439999999999989,0.01999999999999998,1.1439999
> 999999988,-9.39 '::text,
>  '+proj=utm +zone=30 +ellps=intl +units=m +nadgrids +no_defs'::text, 23030)
> AS "GEOMETRY"
>    FROM capa_25830;
> 
> (If we do not include "+nadgrids" we don't get anything, but that is not a
> problem).
> I always get a +-90 meter error.
> 
> Can anybody help me.
> 
> Thanks in advance