R: Areas of Morphological Dilations

dilated.areas {spatstat.geom} | R Documentation

## Areas of Morphological Dilations

### Description

Computes the areas of successive morphological dilations.

### Usage

      dilated.areas(X, r, W=as.owin(X), ..., constrained=TRUE, exact = FALSE)

### Arguments

`X` | Object to be dilated. A point pattern (object of class `"ppp"`), a line segment pattern (object of class `"psp"`), or a window (object of class `"owin"`).
`r` | Numeric vector of radii for the dilations.
`W` | Window (object of class `"owin"`) inside which the areas will be computed, if `constrained=TRUE`.
`...` | Arguments passed to `distmap` to control the pixel resolution, if `exact=FALSE`.
`constrained` | Logical flag indicating whether areas should be restricted to the window `W`.
`exact` | Logical flag indicating whether areas should be computed using analytic geometry (which is slower but more accurate). Currently available only when `X` is a point pattern.

### Details

This function computes the areas of the dilations of `X` by each of the radii `r[i]`. Areas may also be computed inside a specified window `W`.

The morphological dilation of a set X by a distance r > 0 is the subset consisting of all points x such that the distance from x to X is less than or equal to r.

When `X` is a point pattern, the dilation by a distance r is the union of discs of radius r centred at the points of `X`.

The argument `r` should be a vector of nonnegative numbers.

If `exact=TRUE` and if `X` is a point pattern, then the areas are computed using analytic geometry, which is slower but much more accurate. Otherwise the computation is performed using `distmap`.

To compute the dilated object itself, use `dilation`.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### See Also

`owin`, `as.owin`, `dilation`, `eroded.areas`

### Examples

      X <- runifrect(10)
      a <- dilated.areas(X, c(0.1,0.2), W=square(1), exact=TRUE)

[Package spatstat.geom version 2.2-0 Index]