"Good" mesh displays bad (?)

Rhino Rhino for Windows
1

Mesh wizard says this closed mesh is “Good”.
It originally had some self intersecting faces that were fixed after a smoothing operation.
Now it reports some normals that differ from vertex normals.

It displays bad on the viewport unless the normals are flipped inwards.
Rebuild mesh normals doesn’t do anything.
Rebuild mesh doesn’t do anything either
Any quick and simple ideas of what typically causes this ?

MeshRepair Wizard

This is a good mesh.

Important things to consider with this mesh:
Mesh has 2 faces where the face normal differs substantially from the vertex normals.
Although this does not necessarily mean that the mesh is bad,
these normals can cause problems if the ultimate goal is for rendering or boolean purposes.

General information about this mesh:
Mesh does not have any degenerate faces.
Mesh does not have any ngons.
Mesh does not have any extremely short edges.
Mesh does not have any non manifold edges.
Mesh does not have any naked edges.
Mesh does not have any duplicate faces.
Mesh does not have any faces with directions different from the mesh as a whole.
Mesh does not have any self intersecting faces.
Mesh does not have any disjoint pieces.
Mesh does not have any unused vertices.

ID: 89ee626b-3c20-487f-b387-696284a2d8fd (11870)
Object name: COLOR= MATERIAL=  
Layer name: Model::FaceModel
Render Material:
source = from obj
index = 73

Geometry:
Valid mesh.
Closed double precision polygon mesh: 1165655 vertices, 1778784 faces with normals
Bounding box: (-102.02,-19.1064,31.4671) to (101.053,43.5009,317.851)

It displays bad when the normals are out:
Clipboard-1

… but it displays better when the normals are pointing in:
Clipboard-2

2

I would try RebuildMeshNormals command first. If it does not help, I would try UnifyMeshNormals command. If it does not help, I would explode it (with Explode command) and I would use Join command to join the mesh faces into single mesh.

If it still does not help, I would either use QuadRemesh command, or I would use free mesh editing program (Meshmixer or MeshLab).

1 Like
3

that actually can create bad results on a damaged mesh, i at least tried that path once and it did not fix the issues with the mesh. sometimes cutting out damaged parts and patching them might help. also MatchMeshEdge can help in case the mesh does not close or weld properly.

but then the mesh is close and has no issues, i assume that some meshes could be folded into each other, @ThomasAn you might want to post that geometry.

4

The explode command complained about too many triangles, but the weld command did the trick. Many Thanks !