Brent, Very, very usefull info. Thanks. I was just about to reprojecting my data :-) I thought the SRID table was "constrained" to the geometry and you couldn't change it. Seems like that's why the 'virtual' table is there for. Ok, well, I'll give it a try. Thanks for your input !
Regards, Steven On Tue, Apr 8, 2008 at 7:58 PM, Brent Wood <[EMAIL PROTECTED]> wrote: > > --- Steven De Vriendt <[EMAIL PROTECTED]> wrote: > > > Hi list, > > > > I have some data in PostGIS I wish to overlay in Google Maps using WMS > > I'm using the same data in a mapserver application, where EPSG code > > 31300 is used. > > Now for overlay in Google Maps, 4326 is required. > > I have made a copy of my map-file and specified 4326 as projection > > system.Yet, non of my data is showing up. > > > > Do I need to reproject my data for this use ? I thought PostGIS was > > capable of doing reprojection on the fly ? > > Hi Steven, > > Both mapserver & POstGIS can reproject the data on the fly, but they need to > be > told the input & output projections. > > As your data is all displayed via mapserver, the instructions either way will > be in your mapfile. > > To reproject using PostGIS, edit the SQL command in your data statement which > retrieves the PostGIS data. You need to tell PostGIS to return a virtual > table > to mapserver, and transform the data to the required projection in this. Edit > the data line in the layer something like this: > > DATA "new_geom from (select gid, transform(the_geom,4326) as new_geom from > table) as mytable using unique gid using srid=4326" > > > To reproject in mapserver, you need to set the main mapfile projection to > EPSG:4326, using, in the global header part of the mapfile: > > UNITS DD > PROJECTION > "init=epsg:4326" > END > > In the METADATA section, you'll need to set the output projection for WMS, > eg: > METADATA > "wms_title" "My WMS Server" > "wms_srs" "EPSG:4326" > END > > Then in the layer definition, you specify the layer's native projection, so > mapserver can reproject from one to the other: > > LAYER > ... > PROJECTION > "init=epsg:31300" > END > ... > END > > Note that to reproject in PostGIS, Proj.4 support must be compiled into > PostGIS, and similarly for mapserver if you do the reprojection there. If you > compiled these from source, this is not done by default, & you'll need to run > configure with the appropriate flag. If you installed from a package, or on > Windows, proj support is generally built in. > > > HTH, > > Brent Wood > _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
