"Arash" == Arash Partow <arash@partow.net> writes:
Arash> A convex hull is by definition, simply, a set of points. The Arash> cardinality of such a set is infinite. From a geometers point Arash> of view a hull is its own structure or entity and has its own Arash> set of operations. Just because a couple of GIS applications Arash> you've work with in the past seem to have a representation of Arash> CHs that resemble a polygon doesn't mean that has to be the Arash> case. It seems to be more than a cople of GIS applications. For what it is worth, from Wikipedia (http://en.wikipedia.org/wiki/Convex_hull): In mathematics, the convex hull or convex envelope for a set of points X in a real vector space V is the minimal convex set containing X. In computational geometry, it is common to use the term "convex hull" for the boundary of the minimal convex set containing a given non-empty finite set of points in the plane. Unless the points are collinear, the convex hull in this sense is a simple closed polygonal chain. - Maurizio