Ivo Brodien wrote: > Hi Justin, > > i am always amized how quickly you guys answer...thanks. > no problem :) > > On 15.12.2008, at 17:01, Justin Deoliveira wrote: > > >>> SELECT planet_osm_roads.name, planet_osm_roads.way, >>> AsSVG(simplify(st_affine(planet_osm_roads.way,x,0,0,y,tx,ty),2),1) >>> AS assvg >> For a while we have been talking about adding support for on the fly >> queries as feature types... not sure if this falls into your use case. > > Kind of. It is on-the-fly since the output of column "assvg" is computed > on the fly by postgis passing parameters for calculations. How far has > gone the talking? > We sort of have a design for it, but nothing implemented as of yet. Its a pretty big change. >> How exactly are x,y,tx,ty generated? > > They are computed like this: it is simply a affine transformation (scale > and translate) from the lat/lon coords to output screen coords: > > double x = screen.getWidth() / mapExtent.getWidth(); > double y = screen.getHeight() / mapExtent.getHeight(); > > > double tx = -mapExtent.getMinX() * scaleX; > > double ty = (mapExtent.getMinY() * scaleY) + paintArea.getHeight(); > > The view will also have some WHERE (either hard coded or as CQL) clause > for filtering by type of the features. I want to set up a view(layer) > for every zoom level so that only the features for that zoom level get > returned by the database. Or is that a bad approach? I think its a good approach for good performance. The only other alternative is to try and use SLD to do the scale dependence but that won't be nearly as efficient. > > I mean, all the filtering and calculations could be done in my SVG > Renderer in Geoserver but I think it would be much faster within the > database. > Agreed... but getting GeoServer to serve that out will be tricky... > cheers > ivo > > > >
-- Justin Deoliveira OpenGeo - http://opengeo.org Enterprise support for open source geospatial. ------------------------------------------------------------------------------ SF.Net email is Sponsored by MIX09, March 18-20, 2009 in Las Vegas, Nevada. The future of the web can't happen without you. Join us at MIX09 to help pave the way to the Next Web now. Learn more and register at http://ad.doubleclick.net/clk;208669438;13503038;i?http://2009.visitmix.com/ _______________________________________________ Geoserver-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geoserver-devel
