Why are these strange meshes created?

Why is it that when I try to join this polysurface to a planar surface, I get this strange meshing result. More importantly, how do I get a clean join here?
There seem to be no naked edges.

Here is a link to the file Dropbox - Little Aeroplane Nurbs.3dm - Simplify your life


This is typically the mesher choking on the edges.
One way to solve it is set a custom rendermesh for this object.
For windows you would do this ( not sure how that would be done GUI wise on a Mac)

Does that help?

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Yes. Thank you.

@hwansey you may want to mark @Willem s post as solution ?

there is more info about meshing for example here:

"The most important setting here is max distance edge to surface. "

For this specific case i recommend the detailed settings, and use 0.01 mm for max distance edge to surface. Then the strange extra triangles disappear.
you may play arround with the other settings as well.


In my experience a maximum distance edge to surface of 0.01 for the render mesh is much smaller than needed with most geometry, and results in meshes with much larger number of faces than required. I typically use a maximum distance of 1, and very occasionally 0.2. I also usually set a maximum edge length, typically around 4 to 6, and a maximum angle of 1.0 degree.

yes you are right.
i edit my post - the 0.01 are only for the specific case, the artefacts don t disappear with 1.0 or 0.01 … ;-(

Expecting some non planar edges, I deleted the circular surface and tried to cap the rest but it failed. Also some sub-surfaces on the parallel ribs are faulty. You can see through them partially. Not good. Rebuilding from scratch is what I would do.

Also next time you post a file it is better to just upload an export of the relevant geometry right here in the forum.