Newsgroups: comp.graphics
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!hellgate.utah.edu!cs.utah.edu!thomson
From: thomson@cs.utah.edu (Rich Thomson)
Subject: Re: Fractals, and Philosophy of Science
Date: 7 Jan 90 14:39:23 MST
Message-ID: <1990Jan7.143923.8647@hellgate.utah.edu>
Organization: Oasis Technologies
References: <119.256E54C5@uscacm.UUCP> <1247@becker.UUCP> <9144@cbmvax.commodore.com> <6780@lindy.Stanford.EDU> <9215@cbmvax.commodore.com> <12707@phoenix.Princeton.EDU>

In article <12707@phoenix.Princeton.EDU> markv@gauss.Princeton.EDU
    (Mark VandeWettering) writes:
>Because of the hype surrounding fractals, one sees grandiose claims
>about the applicability of fractals to describing natural objects.  
>The problem with this is twofold:
>
>	a)	rarely are such descriptions analytically compared with
>		the objects they describe.  Pictures that are generated
>		with fractals are usually evaluated on purely subjective
>		criteria, which is error prone.
>	b)	descriptions say nothing about the processes that generated
>		the object in the first place.  Fractal mountains don't
>		react to erosion or gravity, fractals trees don't grow with
>		the wind etc....

In an attempt to bring this back around to graphics, think back on the
methods used to generate most computer imagery in use today.  Shading
equations often contain lots of little parameters that are tweaked by the
programmer -- often judged on "purely subjective criteria" in order to get
the best looking image.

That's what I feel graphics is about -- getting the best image for what you
want.  If the image you want comes more easily from a fractal model, who
cares if it isn't a valid "natural model"?  Graphics programmers aren't
geologists or biologists or botanists -- they aren't seeking a model for
explanatory purposes.  They are seeking a model for imaging purposes.  The
two are very different.  Some of these techniques have managed to satisfy
both needs (L-systems for example), but mostly graphics is just a "hack"
that produces a "nice" image.  If you want to completely and accurately
model a mountain, you might as well sketch it by hand because the compute
time necessary to model the complete developmental cycle of a terrain is
prohibitive; not to say that knowledge from the sciences is useless in
helping you obtain a good image, but that the technique used to get a good
image doesn't necessarily have to come from a "scientifically accurate"
model.

						-- Rich
Rich Thomson	thomson@cs.utah.edu  {bellcore,hplabs,uunet}!utah-cs!thomson
	  More Columbians are killed by American cigarettes
		 than Americans by Columbian cocaine