Ok, lets agree on that. For the preserving generalisation I use the JTS TopologyPreservingSimplifier, how to do it for the non preserving case ?
Andrea Aime writes: > Christian Müller ha scritto: >> Looking at the the hint "Hints.PRESERVE_TOPOLOGY" indicates you mean the >> generalization should take place in the FeatureSource ?. Would be >> consistent with the handling of image pyramids. > > Well, in the feature source, yes, where else? You're asking the > feature source to return pre-generalized geometries, where > that does happen internally is an implementation detail. > > What I tried to say is that some generalization techniques do not > preserve topology, they are usually faster than the topology > preserving case: > - for the rendering case we care more about performance and > streaming renderer does not need topologically correct data anyways > - for the wfs case we do want topology preservation instead, so > it's ok to do more work > > I know that for your specific use case it does not make a difference, > as you pre-generalize with a topology preserving algorithm, but what > if tomorrow PostGIS comes out with a generalizing procedure that > is geared towards rendering and performance and does not preserve > topology, and we want to use it "on the fly" to get a speedup > without the hassle of pre-generalizing, configuring and so on? > I'm actually discussing this option with the PostGIS devs, I know > for a fact people that would reject the complex setup of a pyramid > but would be very happy to have a speedup in WMS rendering > without the need to move a finger (as users). > That's why I want to have around a topology preserving case, and > a non topology preserving one, to support the on the fly, > database side, generalization case. > > Cheers > Andrea > > -- > Andrea Aime > OpenGeo - http://opengeo.org > Expert service straight from the developers. ------------------------------------------------------------------------------ _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
