Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!oliveb!apple!versatc!ritter
From: ritter@versatc.UUCP (Jack Ritter)
Newsgroups: comp.graphics
Subject: Re: Ray Traced Bounding Spheres
Summary: Here's a solution
Keywords: Ray trace, bounding volumes, intersection
Message-ID: <17249@versatc.UUCP>
Date: 11 May 89 01:49:21 GMT
References: <17241@versatc.UUCP>
Organization: Versatec, Santa Clara, Ca. 95051
Lines: 27

In article <17241@versatc.UUCP>, ritter@versatc.UUCP (Jack Ritter) writes:
> Given a cluster of points in 3 space, is there
> a good method for finding the minumum radius
> sphere which encloses all the points? 

Several people have responded to this,
so I'll post this. 
Wolfgang (sohrt@cs.utah.edu) suggested an
algorithm, which I dont think was quite right,
but it was good enough to trigger me to come
up with this algorithm:

Take 1st 2 pts, center the initial sphere at mid pt M of the
2 pts, with radius = dist to either.
For each new pt P, if it's outside current sphere,
the new minimum sphere's center will be the
the point midway between P and the intersection of the
line P->M with the old sphere (on side OPPOSITE P). 
This will make an ossculating
sphere that just kisses new pt and old sphere
on opposite sides.
Thanks to Wolfie.
-- 
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