Re: STL file format

From: Michael Brindley
Date: Thursday, September 22, 1994

From: Michael Brindley
To: Ron Jamieson (Cranfield  University)
Date: Thursday, September 22, 1994
Subject: Re: STL file format 
>  Mike ,
> I read your e-mail on the STL file format, If it is public and wanted
> why dont you put on world wide web? I could put it on my server or
> just add a pointer, alternatively you could give it to Elaine Persall.
> As I notice she is quite active in this field!!
Why not?  ... because I haven't written it yet.  I can't do it right
now; someone kindly remind me in a month.

As for WWW ... I have no problem with it being put on such a server,
but first it goes on the obvious and accessible location 
(, I believe is the address for the home of the
'official' net three-dimensional archive).  Even if you have only
a uucp connection to the Internet, you can get files available
for anonymous ftp through email.  I am currently trying to get a
document from cranfield, but have not been able to ftp to it.
If anyone knows of software available for ANY and ALL platforms which
will allow someone to access WWW through a terminal style connection,
let me know!  Then, of course, the document is probably in some
oddball format like html which I'll have to go through numerous
contortions to get in a usuable format.  

Well, enough of that - any further discussions of WWW and related
issues should probably be conducted in private email as it is
off topic for this list.

An earlier poster was having trouble creating STL files that
another piece of software would accept, so here are some
tidbits which might help.

 ***** "Gotchas" for working with binary STL files *****
1.  Numbers are stored in byte-reversed (Intel) order.
    (Least signficant byte first.)  This is likely to be the
    cause of the problem a previous poster had.

2.  The vertices may be in ANY unit of measure and there is 
     no way to tell!  Most files that I have seen use inches
    (admittedly, they were from U.S. sources, so my sample
     may be biased :) ).

3.  The object must be in the first octant - no zero or
    negative coordinates are allowed.  (A silly restriction,
    I guess 3D System's old programmers had trouble with
    addition and subtraction :) ).

  --> Mike Brindley

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