Input Mesh must be Manifold

Issue:

manifold_error.png

I'm trying to create a Quad Mesh, but I keep getting the error: "Input mesh must be manifold."

Applies to:

  • Quad Meshing
  • Export to CAD
  • Mesh export

Cause:

What is Manifold? A topological space that resembles Euclidean space up close. For example, the Earth looks like a plane when you are standing on the surface but from far away it is actually spherical. manifold objects are continuous without any beginning or end. An example of this is a sphere or a cube. A non-manifold object would be a Plane. 

Non-manifold geometry can't exist in real life, which makes this error one we need to solve if we want to 3D print our part. 

A mesh can be non-manifold due to many reasons. Some of the most common occurrences are: 

  • An edge connected to more or less than two faces (including internal facces)
  • Separate regions connected through a single vertex
  • Loose geometry (discontinuous)
  • Plane normals pointing in opposite directions for adjacent faces

To check if your mesh is manifold or not, click on the info (?) panel and go to Properties. There will be a property called Manifold. If it says False, then it is not manifold and if it says True, then it is. 

manifold.png

Solution:

If your mesh isn't manifold, you need to refine your mesh further. This can include using blocks like Remesh Surface, Refine Mesh, Simplify Mesh by Threshold, Simplify Mesh by Amount, or editing the Adaptivity and Feature Size. Take a look at this article for further methods and tips on refining meshes. 

If your mesh is still non-manifold after trying these steps, you may have to go back to your original part in a different program and try cleaning it up. Sending it to another program like Magics for cleaning up may also be necessary. 

If you are trying to create a Quad Mesh using the Quadrangulate Mesh block, you will always want to use one of the refinement blocks mentioned above. Inputting a Mesh from Implicit Body or Mesh from CAD Body block will most likely cause an error when used without a refinement step. 

More on this topic:

Keywords:

 cad error mesh meshing export property quadrangulate quad refine simplify threshold amount vertex input must be manifold euclidean topological space false plane discontinuous normals 
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