From proj4.8 changelog:
"Preliminary support has been added for vertical datums using the
+geoidgrids= directive. The geoidgrids are assumed to provide a
transformation from geoid elevations to ellipsoidal elevations and they
are discussed a bit in the VerticalDatums topic on the web site"
I dont like the st_transform method can change my z coordinates by
default though, dont know if it is because PostGIS is not ready still
for proj4.8 or because it is the proj4.8 default behaviour.
cheers,
Jose
On 27/03/2012 19:02, Jose Carlos Martinez wrote:
Hi, dont know if this is the expected behavior, maybe its because I
built postgis with proj 4.8 or because something has changed in
spatial_ref_sys. Dont know at what time it happened (I missed it).
Before:
pg20=# select st_astext(st_transform(st_geomfromtext('POINT (700000
4500000 100)', 23030), 4326));
st_astext
--------------------------------------------------------------
POINT Z (-0.63662073736203 40.6248036513963 100)
Now:
pg20=# select st_astext(st_transform(st_geomfromtext('POINT (700000
4500000 100)', 23030), 4326));
st_astext
--------------------------------------------------------------
POINT Z (-0.63662073736203 40.6248036513963 168.35361468256)
Using ST_AsKml Its changing the Z coordinate too.
Someone can confirm when this change happened in PostGIS?
Regards,
Jose
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