[postgis-users] problems with transformation

[Obe, Regina]

Check out these threads and Frank's responses.  I suspect its the same issue you are running into. 

http://postgis.refractions.net/pipermail/postgis-users/2008-January/018400.html

http://postgis.refractions.net/pipermail/postgis-users/2008-January/018412.html

Hope that helps,
Regina

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Stefan Zweig
Sent: Thursday, September 18, 2008 7:45 AM
To: postgis-users at postgis.refractions.net
Subject: [postgis-users] problems with transformation

hi list,

im a using two different installations of postgis. the first (1.) is for testing the second (2.) for working.


(1.)
select postgis_full_version()
"POSTGIS="1.3.3" GEOS="3.0.0-CAPI-1.4.1" PROJ="Rel. 4.6.0, 21 Dec 2007" USE_STATS"

(2.)
select postgis_full_version()
"POSTGIS="1.2.1" GEOS="2.2.3-CAPI-1.1.1" PROJ="Rel. 4.5.0, 22 Oct 2006" USE_STATS"


i am running the same query on both installations, getting different results:

(1.)
select st_y (transform(setsrid(makepoint(-626172.139189,7514065.62361),9805), 4326));
55.7765729937296

(2.)
select st_y (transform(setsrid(makepoint(-626172.139189,7514065.62361),9805), 4326));
55.9549116318344

the content for the srids 4326 and 9805 is equal on both installations:

(1.) + (2.)
select * from spatial_ref_sys where srid = 4326 or srid = 9805

srid;auth_name;auth_srid;srtext;proj4text
4326;EPSG;4326;GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]];+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs
9805;EPSG;9805; ;+proj=merc +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +units=m +no_defs


actually i would suppose to get same results on both installations using transform() if the srid entries on both installations are equal. is there another point than the spatial_ref_sys table where the coordinate systems information can be set?

to me it seems like installation (1.) calculates the transformation using a spheroid and (2.) using the wgs84 ellipsoid.


any advices?
thanks in advance + regards. stefan
________________________________________________________________________
Schon gehört? Bei WEB.DE gibt' s viele kostenlose Spiele:
http://games.entertainment.web.de/de/entertainment/games/free/index.html

_______________________________________________
postgis-users mailing list
postgis-users at postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users
-----------------------------------------
The substance of this message, including any attachments, may be
confidential, legally privileged and/or exempt from disclosure
pursuant to Massachusetts law. It is intended
solely for the addressee. If you received this in error, please
contact the sender and delete the material from any computer.