Re: [Jts-topo-suite-user] taking union of large numbers of polygons slow

[Michaël M. <mic...@fr...>]

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