Returns an index matrix to the points of simplices (“triangles”) that form the smallest convex simplicial complex of a set of input points in N-dimensional space. This function interfaces the Qhull library.
String containing extra options for the underlying Qhull command; see details below and Qhull documentation at http://www.qhull.org/html/qconvex.htm#synopsis.
For slient operation, specify the option
dim index matrix of which each row
dim-dimensional “triangle”. The indices
refer to the rows in
p. If the option
provided, then the output is a
list with entries
hull containing the matrix mentioned above, and
vol with the generalised area and volume of the hull
described by the matrix. When applying convhulln to a 3D object,
these have the conventional meanings:
vol is the volume of
enclosed by the hull and
area is the total area of the
facets comprising the hull's surface. However, in 2D the facets of
the hull are the lines of the perimeter. Thus
area is the
length of the perimeter and
vol is the area enclosed.
This is a port of the Octave's (http://www.octave.org) geometry library. The Octave source was written by Kai Habel.
See further notes in
Raoul Grasman, Robert B. Gramacy and David Sterratt [email protected]
Barber, C.B., Dobkin, D.P., and Huhdanpaa, H.T., “The Quickhull algorithm for convex hulls,” ACM Trans. on Mathematical Software, Dec 1996.
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# example convhulln # ==> see also surf.tri to avoid unwanted messages printed to the console by qhull ps <- matrix(rnorm(3000), ncol=3) # generate points on a sphere ps <- sqrt(3)*ps/drop(sqrt((ps^2) %*% rep(1, 3))) ts.surf <- t(convhulln(ps)) # see the qhull documentations for the options ## Not run: rgl.triangles(ps[ts.surf,1],ps[ts.surf,2],ps[ts.surf,3],col="blue",alpha=.2) for(i in 1:(8*360)) rgl.viewpoint(i/8) ## End(Not run)
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