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Date: Thu, 18 Mar 93 09:54:42 -0800
From: Stephan Keith FFD <keith@pioneer.arc.nasa.gov>
Message-Id: <9303181754.AA07308@pioneer.arc.nasa.gov>
To: rman@aero.org
Subject: The RiLine Issue
Cc: keith@pioneer.arc.nasa.gov


Regarding the RiLine issue previously discussed, I was pleased to see that
this is of concern to many of you working with RenderMan out there.

I do scientific visualization, of aerodynamic data presently.  Much of the
analysis involves the depiction of air currents and phenomena as streamlines.
I had thought of using the cylinder method myself, but came up with the
same problems of "chunkiness" (is this a severe case of aliasing, or 
what? :-) ).

I thought what would be useful would be a primitive which allows for a
flexible cylinder, which would be splined (probably bezier derived), with
a variable which defines the diameter of the flexible cylinder.

In a discussion of the water probe (or is it water beast?) in the Abyss,
some ILM computer graphics people discussed the development of something
similar using splined sections; I believe the result employed patches
for rendering, but I am not certain.

In any case, there is a DEFINITE need for some form of flexible cylinder
or tube.  

Thoughts and suggestions are invited - to me directly if necessary.

Cheers and thanks

Stephan R. Keith
keith@pioneer.arc.nasa.gov