[postgis-users] transform params

[toni hernández]

hi,

I have a postgis table with the srid=23031.

If I overlay this table with a WMS on some sofware (gvSIG; ArcGIS), 
everything fits perfectly but when I transform the postgis table to 
23030 and try the overlay to the same WMS (configuring now the WMS to 
work with epsg=23030) the overlay does not fit anymore. There is a 
difference of 70 metres difference (give or take)

And whats more.. if I export my postgis table to a shp file and then use 
the shp file to transform the coordinates from ArcGIS (again from 23031 
to 23030) the overlay with the same WMS fits again.

So I guess postgis is not doing the transformation as I need.

I thinks I have to change some params in the spatial_ref_sys table but 
have no idea what these parameters are.

This is what the spatial_ref_sys for srid=23030 looks like:

srText field:

PROJCS["ED50 / UTM zone 
30N",GEOGCS["ED50",DATUM["European_Datum_1950",SPHEROID["International 
1924",6378388,297,AUTHORITY["EPSG","7022"]],AUTHORITY["EPSG","6230"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4230"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-3],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AUTHORITY["EPSG","23030"]]

proj4Text:
+proj=utm +zone=30 +ellps=intl +units=m +no_defs

 From ArcGIS I have this OUTPUT properties after the transformation:

PROJCS['ED_1950_UTM_Zone_30N',GEOGCS['GCS_European_1950',DATUM['D_European_1950',SPHEROID['International_1924',6378388.0,297.0]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]],PROJECTION['Transverse_Mercator'],PARAMETER['False_Easting',500000.0],PARAMETER['False_Northing',0.0],PARAMETER['Central_Meridian',-3.0],PARAMETER['Scale_Factor',0.9996],PARAMETER['Latitude_Of_Origin',0.0],UNIT['Meter',1.0]]


Anyone can help?

thanks in advance.