Re: Maximum number of triangles in a stl file?

Date: Mon Jun 03 1996 - 19:51:36 EEST

> From: John Dickinson <>
> Dear All,
> I have two quick questions. I have a copy of the Stereolithography
> Interface Spec. from 3D Systems and reading through it I find I have two
> questions:
> 1) on page 4 it says that:
> "Triangle Information
> The triangle counter is 2 to the 16th unsigned integer (65,536)."
> but on page 9 in the binary specification for an STL file it says:
> length 4 bytes (long unsigned integer) for number of facets.
> So if I am creating stl files, is the maximum number of triangles 2^16 or
> 2^32?
The binary spec is correct. Ascii files can have as many triangles as
you have disk space, and binaries use an unsigned long. Provides about
4 gigafacets. I consider 200 kilofacets to be a very large file.

> 2) what is the current best resolution of rapid prototyping machines
> using stl files? I believe it is .005mm.
It depends on the process and the direction of build. For instance,
SLA has layers down to 0.002 inch, but a beam diameter of ~0.010 inch.
So it depends on what kind of resolution you want.

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