The (anti-clockwise) angle through which the ellipse should be
rotated (about its centre) starting from an orientation in which
the axis of half-length a is horizontal.
Logical value controlling the type of approximation
to a perfect ellipse. See Details.
Arguments passed to as.mask to determine the
pixel resolution, if mask is TRUE.
The number of edges in the polygonal approximation to the ellipse.
An object of class owin (either of type “polygonal”
or of type “mask”) specifying an elliptical window.
This command creates a window object
representing an ellipse with the given centre and axes.
By default, the ellipse is
approximated by a polygon with npoly edges.
If mask=TRUE, then the ellipse is approximated by a binary pixel
mask. The resolution of the mask is controlled by
the arguments … which are passed to as.mask.
The arguments a and b must be single positive numbers.
The argument centre specifies the ellipse centre: it can be either
a numeric vector of length 2 giving the coordinates,
or a list(x,y) giving the coordinates of exactly one point, or a
point pattern (object of class "ppp") containing exactly one point.