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From: cs001005@cslab9c.cs.brown.edu (Thomas Colthurst)
Newsgroups: alt.fractals,comp.graphics
Subject: Re: How well does Barnsley's system perform?
Message-ID: <35410@brunix.UUCP>
Date: 6 Apr 90 23:53:12 GMT
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Reply-To: cs001005@cslab9c.cs.brown.edu (Thomas Colthurst)
Organization: Brown Computer Science Dept.
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The thing that disturbs me about Barnsley's claims is not that I don't
believe that he has something, but that the 'veil of mystery' around his
system prevents
me not only from implementing a compression system, but also to doubt
that any efficient means are possible.  That is, all of the IFS
compressed images that we
have seen could have been hand-compressed.  The long time periods are
disturbing
as well -- WE DON'T EVEN KNOW THE ORDER OF THE ALGORITHM THAT DOES THE
COMPRESSION.  IFS compression may be very nice, but if the compression
algorithm is not of polynomial time ...

Does anyone know whether the literature on geometric algorithms
addresses the general problem behind IFS compression, that is, given an
arbitrary shape, find some smaller copies of the shape that can be
positioned to 'collage' it? (Smaller copies being defined as linear
transformations of)  I've seen specific cases of the problem in
brain-teaser books (two smaller rectangles can make a rectange, four
triangles can make up an equilateral triangle) I wonder whether anyone
has attacked the problem in general.

-Thomas C