Given a distance function, find the spatial region where the function value is less than a specified threshold value (or greater than a threshold, etc),
# S3 method for distfun
levelset(X, thresh, compare="A spatial window (object of class "win").
Object of class "distfun" representing the distance function
of a spatial object.
Single numeric value of distance, defining the level set.
Character string specifying one of the comparison
operators "<", ">", "==", "<=", ">=", "!=".
Arguments passed to as.mask if it is necessary to
convert the result to a binary mask.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Rolf Turner rolfturner@posteo.net and Ege Rubak rubak@math.aau.dk.
This is a method for the generic function levelset
which computes level sets of a spatial variable.
A distance function (object of class "distfun" created by
distfun) is a function of spatial location
which measures the distance to a given spatial object.
If f <- distfun(B), where B is some object,
then the level set of f consisting of all spatial locations u
where f(u) <= thresh,
is simply the dilation of the original object B by a distance equal
to thresh. The command levelset(X, thresh) computes this
dilation as a spatial window.
In some cases the object must be converted to a binary pixel mask
and the computation performed by levelset.im. In that
case, any arguments ... are passed to as.mask
to determine the pixel resolution.
distfun,
methods.distfun,
levelset
f <- distfun(cells)
V <- levelset(f, 0.05)
plot(V)
plot(cells, add=TRUE)
Run the code above in your browser using DataLab