RE: STL for ever?

From: Anshuman Razdan (razdan@asu.edu)
Date: Thu Dec 16 1999 - 21:33:39 EET


Georges
        Thanks for completing my proof. Actually the format I suggested is very
close to the MovieBYU format that (i believe) came out in the 70s from BYU
as a early graphics file format. In that since a face could have more than
3 vertices.. the last vertex id was given a '-' sign to indicate closure of
the polygon loop. I was using that for demonstrating that there is light at
the end of the tunnel.

AR

-----Original Message-----
From: owner-rp-ml@ltk.hut.fi [mailto:owner-rp-ml@ltk.hut.fi]On Behalf Of
George Fadel
Sent: Thursday, December 16, 1999 11:39 AM
To: rp-ml@bart.lpt.fi
Subject: RE: STL for ever?

I will not repeat Dr. Anshuman Razdan's demonstration. The STL format is
simple, it has a factor of 3 to 5 data redundancy (useless and leading to
errors), it does not allow easy extension (color and multiple materials),
and academics have tried since the early 90s to convince RP manufacturers,
CAD vendors and users to migrate to a new format.

We have a software to correct STL files, and would definitely profit from
STL remaining the standard, yet, we see the STL as an impediment to the
progress of the technology.
If you the users want the horse and carriage instead of the BMW, then
resist change and continue using the STL format.
If you eventually want color, multi materials, efficiency, etc.. then push
the vendors of RP, of CAD and the academicians to come up with a better
solution. As mentioned earlier, NIST did try to bring the different
constituencies together to affect a change, but only companies with a
significant stake in the technology can force the change.

Note that the format described by Dr. Razdan is a simple VRML format used
in virtual reality applications (and outputted by most CAD vendors). It
could be substituted to STL very easily while a better format is in the
works. One advantage I saw mentioned by Stephen Rock in the exchanges is
that slicing would be much faster - say 2 to 3 times faster on the average.
 Would that be good enough a reason to migrate?

-------------
Georges Fadel
Associate Professor
Mechanical Engineering Department
202 Fluor Daniel EIB
Clemson University
Clemson, SC 29634-0921 USA
Tel: (864) 656-5620
Fax: (864) 656-4435
http://rafiki.vr.clemson.edu/credo/index.htm

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