bdist.points.Rd
\name{bdist.points}
\alias{bdist.points}
\title{Distance to Boundary of Window}
\description{
Computes the distances
from each point of a point pattern
to the boundary of the window.
}
\usage{
bdist.points(X)
}
\arguments{
\item{X}{A point pattern (object of class \code{"ppp"}).}
}
\value{
A numeric vector, giving the distances from each point of the pattern
to the boundary of the window.
}
\details{
This function computes, for each point \eqn{x_i}{x[i]}
in the point pattern \code{X}, the shortest distance
\eqn{d(x_i, W^c)}{dist(x[i], W')} from \eqn{x_i}{x[i]}
to the boundary of the window \eqn{W} of observation.
If the window \code{Window(X)} is of type \code{"rectangle"}
or \code{"polygonal"}, then these distances are computed by
analytic geometry and are exact, up to rounding errors.
If the window is of type \code{"mask"} then the distances
are computed using the real-valued distance transform,
which is an approximation with maximum error equal to the width
of one pixel in the mask.
}
\seealso{
\code{\link{bdist.pixels}},
\code{\link{bdist.tiles}},
\code{\link{ppp.object}},
\code{\link{erosion}}
}
\examples{
data(cells)
d <- bdist.points(cells)
}
\author{\adrian
and \rolf
}
\keyword{spatial}
\keyword{math}