Return the convex hull of a triangulation object
Usage
convex.hull(tri.obj, plot.it=F, add=F,...)
Arguments
tri.obj
|
object of class "tri"
|
plot.it
|
logical, if TRUE the convex hull of
tri.obj will be plotted.
|
add
|
logical. if TRUE (and plot.it=T ), add to
a current plot.
|
Description
Given a triangulation tri.obj
of n points in the plane, this
subroutine returns two vectors containing the coordinates
of the nodes on the boundary of the convex hull.Value
x
|
x coordinates of boundary nodes.
|
y
|
y coordinates of boundary nodes.
|
Author(s)
A. GebhardtReferences
R. J. Renka (1996). Algorithm 751: TRIPACK: a constrained
two-dimensional {Delaunay} triangulation package.
ACM Transactions on Mathematical Software.
22, 1-8.See Also
tri
, print.tri
, plot.tri
, summary.tri
, triangles
, add.constraint
.Examples
# rather simple example from TRIPACK:
tr<-tri.mesh(tritest$x,tritest$y)
convex.hull(tr,plot.it=T)
# random points:
rand.tr<-tri.mesh(runif(10),runif(10))
plot(rand.tr)
rand.ch<-convex.hull(rand.tr, plot.it=T, add=T, col="red")
# use a part of the quakes data set:
quakes.part<-quakes[(quakes[,1]<=-17 & quakes[,1]>=-19.0 &
quakes[,2]<=182.0 & quakes[,2]>=180.0),]
quakes.tri<-tri.mesh(quakes.part$lon, quakes.part$lat, duplicate="remove")
plot(quakes.tri)
convex.hull(quakes.tri, plot.it=T, add=T, col="red")