[R-sig-Geo] Buffers around polygons

[adrian at maths.uwa.edu.au]

Peter Adler asked about constructing a `buffer' around a polygon.

In the spatstat package the function 'dilate.owin' will compute the
morphological dilation (the region of space consisting of all locations
that are less than or equal to d units distant from the original polygon).
The result is not a polygon; it is represented in spatstat as a binary
image.

spatstat will also rescale and translate polygons, etc

spatstat does not have code to construct a *polygonal* buffer (a polygon
with a margin of *at least* distance d from the original polygon) and I
suspect that it's not well defined if the original polygon is not convex.

Adrian Baddeley