dilation: Morphological Dilation

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

Morphological Dilation

Description

Perform morphological dilation of a window, a line segment pattern or a point pattern

Usage

 dilation(w, r, ...)
 ## S3 method for class 'owin'
dilation(w, r, ..., polygonal=NULL, tight=TRUE)
 ## S3 method for class 'ppp'
dilation(w, r, ..., polygonal=TRUE, tight=TRUE)
 ## S3 method for class 'psp'
dilation(w, r, ..., polygonal=TRUE, tight=TRUE)

Arguments

w	A window (object of class "owin" or a line segment pattern (object of class "psp") or a point pattern (object of class "ppp").
r	positive number: the radius of dilation.
...	extra arguments passed to as.mask controlling the pixel resolution, if the pixel approximation is used; or passed to disc if the polygonal approximation is used.
polygonal	Logical flag indicating whether to compute a polygonal approximation to the dilation (polygonal=TRUE) or a pixel grid approximation (polygonal=FALSE).
tight	Logical flag indicating whether the bounding frame of the window should be taken as the smallest rectangle enclosing the dilated region (tight=TRUE), or should be the dilation of the bounding frame of w (tight=FALSE).

Details

The morphological dilation of a set W by a distance r > 0 is the set consisting of all points lying at most r units away from W. Effectively, dilation adds a margin of width r onto the set W.

If polygonal=TRUE then a polygonal approximation to the dilation is computed. If polygonal=FALSE then a pixel approximation to the dilation is computed from the distance map of w. The arguments "\dots" are passed to as.mask to control the pixel resolution.

When w is a window, the default (when polygonal=NULL) is to compute a polygonal approximation if w is a rectangle or polygonal window, and to compute a pixel approximation if w is a window of type "mask".

Value

If r > 0, an object of class "owin" representing the dilated region. If r=0, the result is identical to w.

Author(s)

\spatstatAuthors

See Also

erosion for the opposite operation.

dilationAny for morphological dilation using any shape.

owin, as.owin

Examples

  plot(dilation(redwood, 0.05))
  points(redwood)

  plot(dilation(letterR, 0.2))
  plot(letterR, add=TRUE, lwd=2, border="red")

  X <- psp(runif(10), runif(10), runif(10), runif(10), window=owin())
  plot(dilation(X, 0.1))
  plot(X, add=TRUE, col="red")

spatstat.geom documentation built on Aug. 8, 2025, 6:28 p.m.