Fw: [R-sig-Geo] Voronoi polygons using tripack package....
White.Denis at epamail.epa.gov
White.Denis at epamail.epa.gov
Mon Apr 25 21:54:21 CEST 2005
Assuming the same triangulation algorithm is used in tri.mesh as in
voronoi.mosaic (likely if in the same package, haven't looked at the
details). But see
http://www.cse.unsw.edu.au/~lambert/java/3d/delaunay.html for
alternatives.
r-sig-geo-bounces at stat.math.ethz.ch wrote on 2005-04-25 11:26:34:
> On Mon, 2005-04-25 at 10:18 -0700, White.Denis at epamail.epa.gov wrote:
> > Tripack also calculates the Delauney triangulation (tri.mesh) which
is
> > the dual of the Voronoi tessellation. I haven't looked at the data
> > structure, but the first order neighbors in the triangulation are
also
> > the Voronoi neighbors I believe.
>
> Yes, that has to be true by definition as the Varonoi arcs bisect the
> Delauney arcs.
>
> THK
>
> >
> > r-sig-geo-bounces at stat.math.ethz.ch wrote on 2005-04-25 09:57:13:
> >
> > >
> > >
> > > Greetings:
> > >
> > > We are beginning to use the tripack package to generate voronoi
> > polygons
> > >
> > > for large point datasets. So far the program appears to work well,
> > even
> > > for
> > > datasets in the 100,000 size class.
> > >
> > > One thing we need to do is to identify all of the neighbor
polygons of
> > > each
> > > polygon. Neighbor criteria is: two polygons are neighbors if they
> > share
> > > at
> > > least one edge (line segment).
> > >
> > > The 'cells' and 'methods' method on the voronoi object porport to
find
> > > the neighbors
> > > of veronoi cells. But these operate on the voronoi object, not the
> > > voronoi polygon
> > > object.
> > >
> > > I am wondering if anyone has used or extended the tripack.voronoi
> > > methods to
> > > calculate voronoi polygons and their neighbors, or found a more
> > > suitbable R
> > > package to do so.
> > >
> > >
> > > Thanks in advance,
> > >
> > > Rick Reeves
> > > Scientific Programmer
> > > National Center for Ecological Analysis and Synthesis
> > > UC Santa Barbara
> > >
> > > [[alternative HTML version deleted]]
> > >
> > > _______________________________________________
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> >
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> --
> Tim Keitt
> Section of Integrative Biology
> http://www.keittlab.org/
>
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