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, repair=FALSE)
Arguments
- W
A window (object of class
"owin"
).- repair
Logical value indicating whether to check the validity of the polygon data and repair it, if
W
is already a polygonal window.
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 a rectangle, it is converted to a polygon with
4 vertices.
If W
is already polygonal, it is returned unchanged, by default.
However if repair=TRUE
then the validity of the polygonal coordinates
will be checked (for example to check the boundary is not self-intersecting)
and repaired if necessary, so that the result could be different
from W
.
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
# NOT RUN {
data(letterR)
m <- as.mask(letterR, dimyx=32)
p <- as.polygonal(m)
if(interactive()) {
plot(m)
plot(p, add=TRUE, lwd=2)
}
# }