[postgis-devel] Reprojection issues

[Nico Mandery]

Hello list,

I got a problem reprojecting geometries from EPSG:3785 (the Google or 
Web Mercator projection) to WGS84 (EPSG:4236).
For example when I try to transform one point postgis gives me the 
following - correct - result:

projects=# select 
astext(st_transform(GeomFromText('POINT(879650.162980923 
6108535.16589579)',3785),4326));
                  astext
------------------------------------------
 POINT(7.90203186083991 48.0100993171653)
(1 row)

When I try it again with exactly the same query, I get a wrong result 
and an error from libproj:

projects=# select 
astext(st_transform(GeomFromText('POINT(879650.162980923 
6108535.16589579)',3785),4326));
WARNING:  transform: -38 (failed to load NAD27-83 correction file)
                      astext
--------------------------------------------------
 POINT(1.23892476139034e-06 7.52729195068025e-06)
(1 row)

Every following query will also return wrong results, until I close the 
connection to the database. The first query after establishing a
new connection to postgresql returns a correct result again, every 
following raises the error again.
The NAD correction files exist. Transforming coordinates with cs2cs from 
libproj works without any problems.

I tried it with Postgresql 8.2.4 and 8.3.3 and postgis 1.3.2 and 1.3.3. 
The proj4text in spatial_ref_sys for EPSG:3785 is
"+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 
+k=1.0 +units=m +nadgrids=@null +wktext +no_defs"

Thanks a lot,
Nico