[R] Surface Graphic

[Prof Brian D Ripley]

On Fri, 3 May 2002, Bill Simpson wrote:

> What you need is Delanguay triangulation.
> Here is a demo:
> http://www.cs.cornell.edu/Info/People/chew/Delaunay.html
> You want to do a 3D plot of this, as shown here:
> http://www.colorado.edu/ITS/docs/scientific/idl/3D.html
>
> Not simple in R I don't think, though there apparently there is a package
> akima that allows you to do it.

It is simple using packages deldir and tripack.  But then you need to do
something to interface with persp (notice the use of TriGrid in IDL in your
url).  Interpolation by package akima has already been mentioned, but that
same a number of problems and I would suggest loess or kriging is
preferable: all are covered in spatial statistics books (and the spatial
statistics chapter of Venables & Ripley) and are available in R packages.

> If you figure this out I would be very interested in seeing a simple
> working example.

There are published ones in the references above.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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