How to check whether a model is manifold

If any profile is open, intersects itself or another profile, or contains overlapping curves, the model is non-manifold and may not print correctly.

Types of non-manifold surfaces:

- Naked edges (open surfaces or holes)

- Self-intersecting surfaces

- Intersecting volumes

- Coincident surfaces/edges (overlapping surfaces or edges)






To check whether your model is fit for print, select it and type volume.  If the volume is calculable, then it’s good to go.  Otherwise, you’ll see the message “Some of the objects are not closed.  This calculation is only meaningful if the selected objects fully enclose a volume.  Would you like to continue?”
If Object is closed this is the window you should see. 







In addition, if a model is manifold, then all surface normals will point in the same direction.  To check the surface normals, make sure all the surfaces are joined (Join) and type Dir.  (see more about surface normals below, VOLUMES)


_              Troubleshooting

If the volume is not calculable, then the model is non-manifold.  To check for:

-Naked edges:  Select the object and type ShowEdges.  Both naked edges and coincident edges will be highlighted.

Click Naked Edges to show any part of the model that is not fully closed. 



Keep Naked Edges highlighted (pink)

  • Type DupEdge 
  • Click on highlighted edges
  • Type Patch 
  • Make sure surfaces are not intersecting 
  • Click on all surfaces and type Join 
  • -Self-intersecting surfaces:  No way to check- use MiniMagics

    -Intersecting volumes:  Type Check.  If more than one polysurface object is listed, you have multiple volumes.  Select the model (make sure it’s joined) and type Intersect to identify where the volumes meet.

    -Coincident edges:  Select the object and type ShowEdges.  Both naked edges and coincident edges will be highlighted.

    -Coincident surfaces:  Explode the model (Explode) and type Intersect.  Then, type SelPolyline.  If any polylines are highlighted, there are coincident surfaces.


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