Re: Best STL Repair Tools

From: ATiburon@aol.com
Date: Fri Feb 04 2000 - 03:48:21 EET


In a message dated 2/3/00 7:18:30 PM Eastern Standard Time,
twohlers@compuserve.com writes:

<< Which software product offers the best STL model repair capabilities? I am
 most interested in software that offers a high level of automation. >>
My experience is with SolidView RP Master and of course the good ole 3D
Verify.
In the case of Verify you get virtually no feed back. You have no idea what
if any problems were found and what was done to repair them. But it is
"automatic", if you push the button that is. Of course we have all had files
that would verify fine, but wouldn't build for DoDo.
With SolidView you at least get a report. How many shells, how many unshared
edges. Not how many holes. Also its very easy to spot reversed normals with
the right settings. The documentation lacks any sort of recommendations on
how to proceed with a repair, however. Is it best to analyze normals first or
close the gaps first? Some gaps are acceptable, how big? The tolerance is
adjustable. In the case of a part made from Alias, lots of holes and reversed
normals, or from Surfcam, lots of untrimmed surfaces, you can at least see
the damage somewhat.
When you get a file that has over a hundred shells for instance, you might
muddle through them but basically its a junk file. Same with the untrimmed
surfaces. Might work fine on CNC, but garbage for RP. I guess the bottom line
is that the more control you have, editing triangle etc., the more it becomes
necessary for some kind of intelligence about the repair process. There is
some threshold, where the more you "repair" the worse the file gets. Too many
shells, unshared edges etc. You can see that happen from the analysis. I find
that some of the extraneous shells are very small, 2 or 3 triangles, and can
be deleted without missing them. That sort of analysis could be automated, I
would think. I just spent a good part of today fixing a file. Still to see if
it builds. Sometimes you spend a lot of time and effort, just to find that it
only gets worse. Time to bounce it back to the designer then.
My 10 cents,
Andy Scott
Lockheed Martin Aero Sys

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