Re: [rp-ml] STL files

From: Wesley Brooks <>
Date: Thu Dec 07 2006 - 11:34:24 EET

Is the binary format STL file any different in structure to it's
readable counterpart? Are there still duplicate points? Are normals
still included? I've written readers for the ASCII file format but
since discovered open-source readers for the binary format so haven't
had to learn the finer details of it.

Duplicate points can give problems with rounding errors, some software
could mistake two instances of the same point in different triangles
as different points. This would make the software think it needs to
fix the file, saying so to the user. The user fixes the file, perhaps
automatically and very small, or very high aspect ratio triangles
could be added which can lead to problems when the stl file is further
processed. So you started with a perfect file and ended up with a file
with errors.

Computational power is not so much of a problem these days there isn't
much point wasting power and time by using a format that makes
validating files much more work than it need be. When the file is
stored in a format like the points and IDs it is very simple to check
quality of the file.


Wesley Brooks

C. Brock Rooney <> Wrote:

One thing that I have not seen in this STL go-round is this: The STL spec
also says the ASCII form is for testing and debugging only. It still amazes
me that people would support the ASCII form, since it is much harder to code
and slower to process than the binary form.
Received on Thu Dec 07 10:21:57 2006

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