Date: Fri, 4 Dec 1998 09:01:05 -0800 (PST)
From: Thomas Lumley <thomas@biostat.washington.edu>
To: r-help <r-help@stat.math.ethz.ch>
Subject: Re: contour labelling [was "Re: [R] image ()"]
In-Reply-To: <Pine.OSF.3.95.981203135350.19015A-100000@io.uwinnipeg.ca>
On Thu, 3 Dec 1998, Bill Simpson wrote:
> > include upgrading contour, image, persp etc. In addition I hope that
> > he will also add some mapping facilities along the lines of GMT (using
> > their shoreline database).
> >
> > Now would be a good time to make suggestions about desirable features.
>
> OK this may be a long shot.
> I often have to make a plot of like this: the heights (z) of trees in a
> forest (whose locations are unif rand x,y) are recorded. Now we make a 3D
> shaded surface plot of the (x,y,z) data. A triangular mesh is made by
> finding the Delaunay triangulation (nearest neighbours are connected).
>
> I am not talking about doing some form of interpolation (hence forcing the
> data onto a regular grid).
There is GPLed Delaunay triangulation code in Java (including a fast
approximate algorithm) as part of Visad
(http://www.ssec.wisc.edu/~billh/visad.html). There is an old C
implementation which may well have the same algorithms.
-thomas
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