[ REQ 5391]: convex hull

["Tamara Munzner" <munzner>]

Date: Wed, 10 May 95 13:26:24 -0500
From: nina
To: rgeorge at hsv.tybrin.com
Subject: convex hull


Hi,

Thanks for getting in touch and telling us how you plan to use
our software. 

If your set of points on the sphere all lie within a fairly small
solid angle (which I sure hope is the case for debris fragments),
the best thing to do is project the points from the origin to 
a plane tangent to the sphere somewhere near that solid angle,
and then compute the convex hull of the points in that plane. 
To get back the hull on the sphere, just connect the points on
the sphere (with great-circle arcs) whose projections are connected
with edges in the planar convex hull.

You can compute planar convex hulls with qhull. Also, see my list
of other available computational geometry software at 

http://www.geom.umn.edu/~nina/list.html

Hope this helps. Also, I hope that you are not really using this
information or this software for military applications, since I do
not, knowingly, work on any project that might kill another human being.

Good luck, 
Nina Amenta