dilated.areas
Areas of Morphological Dilations
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, ifconstrained=TRUE
. - ...
- Ignored.
- 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
.
See Also
Examples
X <- runifpoint(10)
a <- dilated.areas(X, c(0.1,0.2), W=square(1), exact=TRUE)