I'm looking for general advice on how to find and repair bad geometry since I've run into this a few times now with models that were made by other people using other CAD programs that I have then imported into MoI and tried to edit.

Generally what are the fastest ways to find problems?

• slivers
• tiny gaps where one surface of a solid gets really close to itself or another surface of that same solid
• degenerate surfaces
• degenerate curves
• self-intersections

I found some posts about this, but the methods seem a little tedious:

http://moi3d.com/forum/lmessages.php?webtag=MOI&msg=7582.1
http://moi3d.com/forum/lmessages.php?webtag=MOI&msg=5786.1
https://moi3d.com/forum/lmessages.php?webtag=MOI&msg=10879.1
http://moi3d.com/forum/lmessages.php?webtag=MOI&msg=5698.1

And I've tried manually doing a binary search by slicing up a model until I find the problem area, but this also takes some patience.

On the repair side, how should I get rid of slivers once I've found them? I just had a case where I tried to do this for an extrusion by extracting the profile curve and then tried Merging the tiny curve segment associated with the sliver with its neighbor, but it turned out that Merge didn't do anything even though the curves are tangent. I also tried untrimming, but the underlying surface didn't extend past the trim curves. Basically, how can I make a large piece out of a large piece and a tiny piece? Or do I need to reconstruct the problem area from scratch?

- Peer

Hi Peer,

re:
> Generally what are the fastest ways to find problems?

It's pretty subtle but often those kinds of problems mean that there will be some overdraw - multiple curves drawn over the same spot on the screen - which will be slightly darker than spots with no overdraw.

Also viewing surface control points can sometimes draw attention to messy spots where points are clumped up, use Edit > Separate then Edit > Show pts. The overdraw is usually more pronounced with the points display and is easier to notice.


For repair, it kind of depends on the particular situation. If the fragment is small enough it can be possible to separate it out and delete it and rejoin the surrounding surfaces together. In other cases surrounding surfaces may need to be untrimmed and retrimmed or constructed as a longer surface.

- Michael

Hi Michael,

Thanks for the tips about overdraw, showing control points, and removing fragments.

- Peer