Andrea:
Thank you for your insight. My issue is that I am trying to put my layer on top of a google map, which requires srid 900913. I am assuming that at some point I need to do the reprojection from 2163 to 900913, and geoserver WMS seems to be the right place. do you know if there is a way to make EPSG:3785 work with Google maps? I could try storing my points in Postgis as 900913, so no reprojection is needed, but I would like to avoid that. Thanks again. Alex From: [email protected] [mailto:[email protected]] On Behalf Of Andrea Aime Sent: Thursday, March 03, 2011 2:13 AM To: [email protected] Cc: [email protected] Subject: Re: [Geoserver-users] Help with reprojection On Thu, Mar 3, 2011 at 2:04 AM, <[email protected]> wrote: I would appreciate any help with the following I have a postgres/postgis database that has a table with points using srid = 2163. If I do: SELECT ST_AsEWKT(ST_Transform((select spatial_location from vw_maps where id=1),900913)); I get "SRID=900913;POINT(-13672282.345767 5705158.43996816)", which is the right reprojection for my point. If I define a layer in GeoServer pointing to that same table (which means it will assume 2163) and use OpenLayers (or uDig) to request a 900913 layer, that same point now comes back as -13672358.78089 573596.56157 Notice the shift on the second value. All my values are shifted up ! I tried everything, even comparing the definitions of 900913 in Postgis, Geoserver and uDig, and they are all the same PROJCS["WGS84 / Google Mercator", GEOGCS["WGS 84", DATUM["World Geodetic System 1984", SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]], AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]], UNIT["degree", 0.017453292519943295], AXIS["Longitude", EAST], AXIS["Latitude", NORTH], AUTHORITY["EPSG","4326"]], PROJECTION["Mercator_1SP"], PARAMETER["semi_minor", 6378137.0], PARAMETER["latitude_of_origin", 0.0], PARAMETER["central_meridian", 0.0], PARAMETER["scale_factor", 1.0], PARAMETER["false_easting", 0.0], PARAMETER["false_northing", 0.0], UNIT["m", 1.0], AXIS["x", EAST], AXIS["y", NORTH], AUTHORITY["EPSG","900913"]] Can someone give me a hint here? Thanks,Alex This was discussed some time ago on the mailing list. 900913 does have the same WKT definition in various systems, but the WKT definition misses some important details that make the definition be interpreted in different ways by different systems. If you want an interoperable one use EPSG:3785 instead, that has a proper definition that should be interpreted in a uniform way by different systems: http://demo1.geo-solutions.it/geoserver/web/?wicket:bookmarkablePage=:org.ge oserver.web.demo.SRSDescriptionPage <http://demo1.geo-solutions.it/geoserver/web/?wicket:bookmarkablePage=:org.g eoserver.web.demo.SRSDescriptionPage&code=EPSG:3785> &code=EPSG:3785 Cheers Andrea -- ------------------------------------------------------- Ing. Andrea Aime GeoSolutions S.A.S. Tech lead Via Poggio alle Viti 1187 55054 Massarosa (LU) Italy phone: +39 0584 962313 fax: +39 0584 962313 mob: +39 333 8128928 http://www.geo-solutions.it http://geo-solutions.blogspot.com/ http://www.youtube.com/user/GeoSolutionsIT http://www.linkedin.com/in/andreaaime http://twitter.com/geowolf -------------------------------------------------------
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