as.polygonal
Convert a Window to a Polygonal Window
Given a window W
of any geometric type (rectangular,
polygonal or binary mask), this function returns a polygonal window
that represents the same spatial domain.
Usage
as.polygonal(W)
Arguments
- W
- A window (object of class
"owin"
).
Details
Given a window W
of any geometric type (rectangular,
polygonal or binary mask), this function returns a polygonal window
that represents the same spatial domain.
If W
is already polygonal, it is returned without change.
If W
is a rectangle, it is converted to a polygon with
4 vertices.
If W
is a binary mask, then each pixel in the
mask is replaced by a small square or rectangle, and the union of these
squares or rectangles is computed. The result is a polygonal window
that has only horizontal and vertical edges.
(Use simplify.owin
to remove the staircase
appearance, if desired).
Value
- A polygonal window (object of class
"owin"
and of type"polygonal"
).
See Also
Examples
data(letterR)
m <- as.mask(letterR, dimyx=32)
p <- as.polygonal(m)
if(interactive()) {
plot(m)
plot(p, add=TRUE, lwd=2)
}