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Old 14th December 2021, 09:11 PM   #1
JeffRay
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Default Selecting polygons with 2 vertices

I have a model with numerous degenerate polygons, each containing only 2 vertices. I wish to delete them. I cannot see a way to select only them, nor does "Optimize surfaces..." find and delete them.

Am I doing something wrong, or is there another way to select and delete them?

Thanks.
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Old 15th December 2021, 08:18 AM   #2
Andy
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Default Re: Selecting polygons with 2 vertices

In Surface select-mode, use Edit->select-surfaces->Invalid-poly, then press delete.
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Old 15th December 2021, 12:15 PM   #3
JeffRay
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Default Re: Selecting polygons with 2 vertices

Thank you for the prompt reply!

Unfortunately, this results in an empty selection. Through experimentation, I have found 2 partial solutions, but neither gets me all the way there.

The first way is to manually select the 2 vertexes in "vertex mode", then switch to "surface mode", and the bad surface will then be selected. Obviously, with many thousands of verts, I don't want to walk the entire model doing this.

The second way is to select all triangles and then "Cut Away" the objects. This works better, but unfortunately makes a mess of the hierarchy because not everything is a triangle, and it is time consuming to reassemble the model afterwards.

Is it possible there is something wrong in my model that would prevent "select invalid polygons" from working? I've already made sure everything is a polygon (not line or polyline).

Thanks!
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Old 15th December 2021, 05:48 PM   #4
Andy
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Default Re: Selecting polygons with 2 vertices

An invalid poly could be two vertices or perhaps more where the vertices are same or edges are crossing.


Try optmizing vertices and see if any vertices are removed.
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Old 15th December 2021, 09:49 PM   #5
JeffRay
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Default Re: Selecting polygons with 2 vertices

That did the trick. About 1% of the time it removed the wrong geometry, but 99% of the time it worked great.

Thanks!
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Old 17th December 2021, 06:59 PM   #6
Tomkat
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Default Re: Selecting polygons with 2 vertices

Quote:
Originally Posted by Andy View Post
In Surface select-mode, use Edit->select-surfaces->Invalid-poly, then press delete.
I just wanted to chime in to say that I also always get "nothing selected" when I run this... even when I can see invalid polys.
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Old 18th December 2021, 10:00 AM   #7
Andy
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Default Re: Selecting polygons with 2 vertices

If you create a polygon with only two vertices, does that not select?
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Old 19th December 2021, 11:43 AM   #8
Tomkat
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Default Re: Selecting polygons with 2 vertices

I will try to take a screenshot the next time I am working on a model.
Maybe the surfaces have 3 vertices, but 2 of them are in the exact same spot, somehow?

EDIT: I believe that is indeed what they are. To test... draw a triangle, then move one of the vertices to the exact location of one of the other two. What you have now APPEARS to be a line, but it's actually an "invalid" polygon. However, the "select invalid poly" tool won't select it.
(It's difficult to see here, but it's just to the left of the axis indicator.)



Note: I don't do this intentionally, but it's extremely common to have these "left over" invalid polygons when working on models, doing various operations, etc.

Last edited by Tomkat; 19th December 2021 at 11:52 AM.
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Old 19th December 2021, 02:14 PM   #9
Andy
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Default Re: Selecting polygons with 2 vertices

Menu Vertex->Optimize Vertices will remove the duplicate vertices.
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