# 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)
}
# }
```

*Documentation reproduced from package spatstat, version 1.63-2, License: GPL (>= 2)*