Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!yale!quasi-eli!cs.yale.edu!musgrave-forest
From: musgrave-forest@cs.yale.edu (F. Ken Musgrave)
Newsgroups: comp.graphics
Subject: Re: PoolTable Turing Test Photo
Message-ID: <28386@cs.yale.edu>
Date: 26 Jan 91 13:33:58 GMT
References: <7926@castle.ed.ac.uk> <28220@cs.yale.edu> <1991Jan25.142659.3914@jarvis.csri.toronto.edu>
Sender: news@cs.yale.edu
Organization: Yale University Computer Science Dept., New Haven, CT 06520-2158
Lines: 30
Nntp-Posting-Host: systemsy-gw.cs.yale.edu
Originator: musgrave@bugs.CS.Yale.Edu

In article <1991Jan25.142659.3914@jarvis.csri.toronto.edu> stam@dgp.toronto.edu (Jos Stam) writes:
>Why are fractals so important? Any stochastic model will do. One way to add
>"dirt" is by texture mapping or solid texturing. (see for example the cover
>of the Renderman manual).

  Yes, the reference to fractals in my posting was a bit indicative of my 
peculiar world view.  Fractals are the most compact way of describing
complexity in nature.  "Dirt", in order to be realistic, should be complex.
It can also be quite heterogeneous and thereby non-fractal, as it is the
quality of self-similarity that characterizes fractals.

  By the same token, no simple texture can represent dirt well.  A hand-painted
texture map is trivial; you might as well scan photographs of dirt and
scuffing.  If it's not described with a formula or an algorithm it's not
computer graphics, it's art or craft.  (Again, I'm showing my prejudice in
favor of procedural models.)

  Have a good close look at a "trompe l'oeil" still life painting (e.g., Ken
Davies) to get an example of the kind of complexity involved in artful 
depiction of dirt and wear.  We have a long way to come, in computer graphics.
Yet the inclusion of such imperfections is essential to the computer graphics
"Turing test", and to the aesthetic flexibility of the computer as a medium for
visual art.

						Soap Boxken

-- 
		The Fundamental Dilemma of Existentialism:

	Eschew obfuscation.			Ignore alien orders.