spatstat.geom (version 3.7-0)

levelset.distfun: 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 distfun
levelset(X, thresh, compare="

Value

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

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.

See Also

distfun, methods.distfun, levelset

Examples

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