It should be, our spatial_ref_sys is generated from gdal which generates from epsg. You have a pretty recent postgis, so I'm surprised it's missing. P
On Tue, Aug 17, 2010 at 1:57 AM, Erik Rehn <e...@slagkryssaren.com> wrote: > Thank you guys! You were right, I had flipped the coordinates in the test I > made. > > But that didn't explain the error I got in the KML. The solution to that > was to add "+towgs84=414.1,41.3,603.1,-0.855,2.141,-7.023,0" to the > spatial_ref_sys table for srid 3021. Why isn't that in there by default? > > erik > > On 2010-08-12 17:05, Ricardo Bayley wrote: >> >> very nice explanation Mike >> >> On Thu, Aug 12, 2010 at 11:39 AM, Mike Toews <mwto...@gmail.com >> <mailto:mwto...@gmail.com>> wrote: >> >> Hi, >> >> Your coordinates may be flipped. Was it 59N 18E? If so, use x,y >> notation: 'POINT(18 59)', which results in 'POINT(18.0000000000006 >> 58.9999999999905)', which is close enough. >> >> Also keep in mind that you are outside the projection bounds: >> http://spatialreference.org/ref/epsg/3021/ (just a bit too far east). >> Whenever you are outside the projection bounds, the likelihood of >> storage precision errors increase. To understand why this is, you can >> think of taking the tangent of a two angles that are nearly a >> right-angle (89.9991 and 89.9992) which have very different results >> due to nature of the geometry. >> >> -Mike >> >> On 11 August 2010 13:10, Erik Rehn <e...@slagkryssaren.com >> <mailto:e...@slagkryssaren.com>> wrote: >> > Hello Postgis Users! >> > >> > This is my first post on this list so I will start by asking >> > a simple (and probably stupid) question. :) >> > >> > While using ST_AsKml() to produce an overlay for Google Earth I >> > noticed that all my geometries where shifted slightly south-east. >> > I figured this had something to do with the transformation between >> > the projection that my geometries are stored in (SRID 3021) and >> WGS84 (4326) >> > that is outputted by ST_AsKml() >> > >> > Just to test I ran this: >> > >> > SELECT ST_AsText( >> > ST_Transform( >> > ST_Transform( >> > ST_GeomFromText('POINT(59 18)',4326), >> > 3021), >> > 4326)); >> > >> > I input a point in WGS84 (59,18), transforms it to 3021 and then >> back to >> > WGS84. The result I get is: >> > POINT(58.8672757036296 18.0394763349359) >> > >> > Can anyone explain this? Am I missing something regarding >> ST_Transform()? >> > >> > Im running Postgis 1.5 on Windows. >> > >> > Thank you for any help! >> > /Erik >> > >> > -- >> > Erik Rehn >> > Slagkryssaren >> > e...@slagkryssaren.com <mailto:e...@slagkryssaren.com> >> > www.slagkryssaren.com <http://www.slagkryssaren.com> >> > _______________________________________________ >> > postgis-users mailing list >> > postgis-users@postgis.refractions.net >> <mailto:postgis-users@postgis.refractions.net> >> > http://postgis.refractions.net/mailman/listinfo/postgis-users >> > >> _______________________________________________ >> postgis-users mailing list >> postgis-us...@postgis.refractions.net >> <mailto:postgis-users@postgis.refractions.net> >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> >> > > -- > Erik Rehn > Slagkryssaren > e...@slagkryssaren.com > www.slagkryssaren.com > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
