Either way, the union of a polygonal coverage is a common special case that would benefit from having its own algorithm. I implemented this for PostGIS a couple of years ago, though there didn't seem to be much interest at the time [1]. It's probably a better fit for GEOS anyway. I wrote a fairly ugly Java implementation several years ago [2] that I could re-do to take advantage of recent polygonizer improvements and bring into GEOS.
Dan [1] https://lists.osgeo.org/pipermail/postgis-devel/2016-April/025784.html [2] https://github.com/dbaston/CoverageOp/tree/master/src/main/java/org/dbaston/coverageop On Tue, Apr 16, 2019 at 11:06 AM Martin Davis <mtncl...@gmail.com> wrote: > That's good to know, Darafei. Can you provide a data example that we can > use for doing performance testing? > > I'm not seeing that JTS buffer(0) is slower than union() on a random > triangulation. So perhaps either your dataset has some different > characteristic, or possibly GEOS buffer has different performance > characteristics to JTS. > > On Tue, Apr 16, 2019 at 5:27 AM Darafei "Komяpa" Praliaskouski < > m...@komzpa.net> wrote: > >> Hello, >> >> >>> Ultimately I think the ideal approach is going to be abandoning >>> CascadedUnion and switch to a full union algorithm (which will essentially >>> be the same as running buffer(0). This should have very good performance. >>> >> >> We're using PostGIS's ST_Union to dissolve a clipped TIN into a polygon. >> Current ST_Union implementation handles this measurably faster than >> ST_Buffer(ST_Collect(geom),0). Please keep this case in mind. >> >> >> -- >> Darafei Praliaskouski >> Support me: http://patreon.com/komzpa >> _______________________________________________ >> geos-devel mailing list >> geos-devel@lists.osgeo.org >> https://lists.osgeo.org/mailman/listinfo/geos-devel > > _______________________________________________ > geos-devel mailing list > geos-devel@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/geos-devel
_______________________________________________ geos-devel mailing list geos-devel@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/geos-devel
