spatstat (version 1.9-0)

distmap.owin: Distance Map of Window

Description

Computes the distance from each pixel to the nearest point in the given window.

Usage

## S3 method for class 'owin':
distmap(X, \dots)

Arguments

X

A window (object of class "owin").

...

Arguments passed to as.mask to control pixel resolution.

Value

• A pixel image (object of class "im") whose greyscale values are the values of the distance map. The return value has an attribute "bdry" which is a pixel image.

Details

The ``distance map'' of a window $W$ is the function $f$ whose value f(u) is defined for any two-dimensional location $u$ as the shortest distance from $u$ to $W$.

This function computes the distance map of the window X and returns the distance map as a pixel image. The greyscale value at a pixel $u$ equals the distance from $u$ to the nearest pixel in X.

Additionally, the return value has an attribute "bdry" which is also a pixel image. The grey values in "bdry" give the distance from each pixel to the bounding rectangle of the image.

If the window X is not already a pixellated window (a binary image mask), it is converted into one. The arguments ... control the pixel resolution in this case, but will otherwise be ignored. This function is a method for the generic distmap.

See Also

distmap, distmap.ppp

Examples

data(letterR)
  U <- distmap(letterR)
  plot(U)
  plot(attr(U, "bdry"))