ANNOUNCE: ADMesh - Solid Mesh Processor

From: Anthony Martin (California State  University, Long Beach)
To: RP-ML
Date: Wednesday, July 26, 1995
Subject: ANNOUNCE: ADMesh - Solid Mesh Processor
ADMesh is a program for processing triangulated solid meshes.  Version 0.9
is the first public release and currently it only supports the STL file
format that is used for rapid prototyping applications.

Features:
---------
 * Read and write binary and ASCII STL files
 * Check STL files for flaws (i.e. unconnected facets, bad normals)
 * Repair facets by connecting nearby facets that are within a given tolerance
 * Fill holes in the mesh by adding facets.
 * Repair normal directions (i.e. facets should be CCW)
 * Repair normal values (i.e. should be perpendicular to facet with length=1)
 * Remove degenerate facets (i.e. facets with 2 or more vertices equal)
 * Translate in x, y, and z directions
 * Rotate about the x, y, and z axes
 * Mirror about the xy, yz, and xz planes
 * Scale the part by a factor
 * Merge 2 STL files into one

 ** ADMesh outputs the following statistics after processing:

================= Results produced by ADMesh version 0.9 =================
Input file         : sphere.stl
File type          : Binary STL file
Header             : Processed by ADMesh version 0.9
============== Size ==============
Min X = -1.334557, Max X = 1.370952
Min Y = -1.377953, Max Y = 1.377230
Min Z = -1.373225, Max Z = 1.242838
========= Facet Status ========== Original ============ Final ====
Number of facets                 :  3656                3656
Facets with 1 disconnected edge  :    18                   0
Facets with 2 disconnected edges :     3                   0
Facets with 3 disconnected edges :     0                   0
Total disconnected facets        :    21                   0
=== Processing Statistics ===
Number of parts       :     1
Degenerate facets     :     0
Edges fixed           :    24
Facets removed        :     0
Facets added          :     0
Facets reversed       :     0
Backwards edges       :     0
Normals fixed         :     0

There are two different algorithms used for fixing unconnected facets.  The
first algorithm finds an unconnected edge, and then checks nearby within a
given tolerance for another unconnected edge.  It then fixes edges within
tolerance.  Some meshes can be completely fixed just using this method.  If
there are still unconnected facets after this "nearby check" has been done,
then a second algorithm is used.  This algorithm just fills any holes in the
mesh by adding facets until all of the holes are filled.  Using these two
algorithms, almost any imperfect STL file can be "fixed" 100% so that there
are 0 unconnected facets.  Whether the resulting mesh is what you really
want is another question since there is no way for ADMesh to add information
that isn't there.

I know that there are other file formats besides STL that represent solid
parts in the form of a triangulated mesh.  For example, I believe that some
forms of DXF file and several raytracing file formats are like this.  It
would not be difficult to add read/write/translate capabilities to ADMesh
for these files.  If anyone knows of a similar format that they want
supported, please send me a small sample or a description of such a format
and I will add support for it.

At this point ADMesh is only command-line driven and has no windowing
capabilities.  This should make it extremely easy to port to any UNIX-like
system, and it shouldn't have any problems compiling on Windows NT, and it
probably even compiles under DOS or Windows since it doesn't use any
UNIX-specific system calls as far as I know.  However, the silly DOS memory
allocation could cause problems for larger files.

ADMesh was developed on a 486/66 with 16Mb running the Linux operating system.
It has also been compiled and run on the following systems:
SunOS 4.1.3
IRIX  5.2
Please let me know about successes or failures with other systems.

On my Linux system with 16Mb of memory, I can easily process files that have
up to about 200,000 facets.  Files larger than this can be processed, but
the system begins to slow down significantly due to swapping.  A system with
more memory will be able to process greater numbers of facets more easily.
Following are some indications of process times:
40,000  facets: 10 seconds
80,000  facets: 20 seconds
160,000 facets: 50 seconds
320,000 facets: 13 minutes (heavy swapping occurred)

There are a few features that are "missing" from ADMesh but that might be
added in the future.  These include:
 * Display capability
 * Slicing
 * Splitting a file into smaller files

ADMesh is free but Copyrighted software.  It is distributed under the terms
of the GNU General Public License (GPL).  It is NOT in the public domain and
its source code cannot be used in commercial software.  Details of the GPL
are in the file COPYING that comes with the ADMesh software package.

ADMesh can be obtained via http from:
  http://www.engr.csulb.edu/~amartin/admesh/admesh-0.9.tar.gz
or visit my home page at:
  http://www.engr.csulb.edu/~amartin

If anyone has trouble getting this file via http, first, you might try the
following command:
lynx -source http://www.engr.csulb.edu/~amartin/admesh/admesh-0.9.tar.gz
                                                        > admesh-0.9.tar.gz

If you still can't get it, please let me know.  I am still waiting for a
response from the sysadmin at CSULB regarding an anonymous ftp directory.

ADMesh version 0.9 can be considered beta software.  It has a version number
less than 1.0 not because I think that it is particularly buggy, but I am
the only person who has tested it so far.

Send questions, comments, suggestions, etc. to me at the following address.
<amartin@engr.csulb.edu>
Anthony D. Martin
------------------------------------------------------------------------------
Dear Ken,
     Please take a look at this and see if it would save you some work on 
your StL viewer. No use redoing the already-done, and this s/w is free! 
Why don't you download it and take a look at it.