As it happens, I have also been looking into this. I began by
considering
Ken Clarkson's hull: http://www.netlib.org/voronoi/hull.html but
eventually
discovered that its alpha shapes don't seem to treat holes in regions,
only
simply connected regions. (I would be happy to hear to the contrary, if
someone has other experience.) There is a nice matlab implementation
http://www.mathworks.com/matlabcentral/fileexchange/6760 which I've
also experimented with using R.matlab, but this is still very early
days.
The matlab version is only 2d, whereas Clarkson does "moderate d"
which
extends at least to 3d.
Given tripack, it seems like alpha-shapes shouldn't be such a big
enterprise, and
might make a nice project for someone with an interest in computational
geometry. Hint, hint. Nudge, Nudge.
url: www.econ.uiuc.edu/~roger Roger Koenker
email rkoen...@uiuc.edu Department of Economics
vox: 217-333-4558 University of Illinois
fax: 217-244-6678 Champaign, IL 61820
On Feb 18, 2009, at 7:20 AM, Pedroso MOACIR wrote:
Hi all,
I want to approximate te shape of an area defined by a set of points.
The convex hull is not good enough, but I think that an alpha shape
would be fine. I did an RSiteSearch(), google search, RSeek.org
search,
looked at the CRAN Views, but was unable do find a function in R that
computes the alpha shape. Does anyone know if there is such a
function
in R?
Theank you very much.
Moacir Pedroso
Embrapa - Brazil
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
