Manifold - Non Manifold

Hello Everyone,

Other than boolean operations, what problems might one encounter with non-manifold geometry in Blender?

Thanks for your time!!

I have gotten really badly messed up normals from them.
(hint) control-N recalculates and can fix this.

Extrude dup fails badly. Spin dup seems to work ok.

Let’s see

They mess up booleans
They mess up normals
You try to shrink/flatten them you may get poor results
Subsufing will mess up badly
Set smooth will create black lines.

Than you all for the replies,

Non-Manifold sounds like something that should be avoided for anything other than a single plane surface - floor for example.

Thanks again!

One of the only things non manifold is okay on is flat shaded surfaces. Or smooth walls on top of a flat shaded object. Otherwise you might want to avoid it.

The decimate modifier doesn’t seem to work on non-manifold meshes.