levelset.distfun: Level Set of a Distance Function

In spatstat.geom: Geometrical Functionality of the 'spatstat' Family

Level Set of a Distance Function

Description

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),

Usage

## S3 method for class 'distfun'
levelset(X, thresh, compare="<=", ...)

Arguments

X	Object of class "distfun" representing the distance function of a spatial object.
thresh	Single numeric value of distance, defining the level set.
compare	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.

Details

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.

Value

A spatial window (object of class "win").

Author(s)

\spatstatAuthors

.

See Also

distfun, methods.distfun, levelset

Examples

  f <- distfun(cells)
  V <- levelset(f, 0.05)
  plot(V)
  plot(cells, add=TRUE)

spatstat.geom documentation built on Jan. 20, 2026, 5:08 p.m.