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From: pyle@lll-lcc.UUCP
Newsgroups: comp.graphics
Subject: Scan Converting Quadric Surfaces
Message-ID: <927@lll-lcc.aRpA>
Date: Thu, 18-Jun-87 00:45:10 EDT
Article-I.D.: lll-lcc.927
Posted: Thu Jun 18 00:45:10 1987
Date-Received: Fri, 19-Jun-87 04:00:13 EDT
Organization: Lawrence Livermore Labs, Livermore Ca
Lines: 24
Keywords: Scan Conversion, Quadric Surfaces


I submitted this request once before, but I would like to submit it again.  Does
anyone know of a general way of scan-convert quadric surfaces?	I have had
much sucess using Blinn's methods (see "The Algebric Properties of Homogeneous
Second Order Surfaces", James F. Blinn), but his methods appear to fail on
cones and cylinders (it's hard to determine the sillouette plane).  I have read
two papers that seem to indicate that uniform processing of quadrics is
possible.  The papers are:


"Visible Surface Algorithms for Quadric Patches", Robert Mahl, IEEE TOC,
Jan. 1972.

"A Parametric Algorithm for Drawing Pictures of Solid Objects Composed of
Quadric Surfaces", Joshua Levin, Comm. of the ACM, Oct. 1976.



Any help is appreciated.


Thanks,

Ernie Pyle