dilated.areas {spatstat} | R Documentation |
Computes the areas of successive morphological dilations.
dilated.areas(X, r, W=NULL, ..., exact = FALSE)
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 |
Optional. Window (object of class "owin" ) inside which the areas
will be computed, or NULL indicating the entire area
should be computed.
|
... |
Ignored. |
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.
|
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
.
Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner r.turner@auckland.ac.nz
owin
,
as.owin
,
dilation
,
eroded.areas
X <- runifpoint(10) a <- dilated.areas(X, c(0.1,0.2), W=square(1), exact=TRUE)