From: broehl@sunee.uwaterloo.ca (Bernie Roehl)
Subject: Re: INFO: Metaballs?
Date: Wed, 30 Jun 1993 11:30:37 GMT
Organization: University of Waterloo



In article <20rgv0$b80@news.u.washington.edu> wright@sunny.dab.ge.com
(Michael Wright) writes:

>I recently saw a magazine article on METABALLS. It was the way some of
>the animation of Jurastic Park was done.

As I recall, a metaball is a kind of "equipotential surface" around a
point.  You specify a point, a radius, and an "intensity" for each
ball; when balls come close, their shapes blend to form a smooth
equipotential surface.

They seem to be very useful for modelling shapes like animals and
humans.  The idea is that each joint (say, shoulder or knee or elbow)
would be a metaball; the thigh would be the equipotential surface
formed by the proximity of the hip and knee metaballs.  The knee and
ankle metaballs define the calf, and so on.

I haven't used them, so this is all third-hand.  They can be rendered
by most raytracing packages (I believe they're also called "blobs" or
"soft spheres" or "fuzzy spheres"), but they can't be rendered in
real-time (so they're not useful for VR, at least not yet).

-- 
	Bernie Roehl
        University of Waterloo Dept of Electrical and Computer Engineering
	Mail: broehl@sunee.UWaterloo.ca
	Voice:  (519) 885-1211 x 2607 [work]