Re: [Jts-topo-suite-user] taking union of large numbers of polygons slow
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From: Michaël M. <mic...@fr...> - 2012-10-17 21:47:51
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Hi, > > Ah, so you have set of points and want to find a representative shape > for them? That's a bit of a different problem. > > > Well, what I actually have is a set of points, which I DIY-buffer (by > drawing a circle around each of them) and then union. I'd be equally > happy with an alpha shape based on those points which I then buffer to > some distance to approximate the unioned circles. If working in a gis environment is an alternative for you, you may want to test Eric's concave hull plugin for OpenJUMP (based on JTS) http://www.rotefabrik.free.fr/concave_hull/ Michaël > > > > > In theory using unary union (cascaded union) should be fairly > memory-efficient, since lots of internal segments get thrown away as > the unions get larger. But this depends pretty heavily on the > dataset. It may be that the CascadedUnion code is hanging onto memory > unecessarily - it would be good to know if that is the case. > > > I'll try and get a before and after histogram of the heap by class as > a starting point. > > > > ------------------------------------------------------------------------------ > Everyone hates slow websites. So do we. > Make your web apps faster with AppDynamics > Download AppDynamics Lite for free today: > http://p.sf.net/sfu/appdyn_sfd2d_oct > > > _______________________________________________ > Jts-topo-suite-user mailing list > Jts...@li... > https://lists.sourceforge.net/lists/listinfo/jts-topo-suite-user |