My mesh object is based on a CT bone scan so there are many inner geometries due to natural spaces in human bones. But I need a model that has no inner geometries. How do I fill inner holes and spaces with completely solid mesh?


Update: I attached a screenshot of the "holes" in my mesh after boolean op.

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1 Answer 1


If your geometry has true interior faces

see an older version of the answer:

If there is no disjoint interior geometry.

a manual way..

  • First in edit mode unselect all geometry.
  • use box select (b) to select the visible outer faces, and rotate the model around and add to the selected set by doing more box selects until all outer faces are selected. You can also use the other selection methods, C enters a mode that lets you "paint" selections by leftclicking and dragging the mouse around (esc to exit that mode).
  • Then hit Z to see the model as see-through, you'll notice many unselected verts, those would be considered interior for your purposes.
  • Ctrl+I to invert selection. enter image description here
  • X , delete vertices.


The problem then would be that the model now has holes that need to be filled.

A strategy to continue this in Blender is to select all edges that only attach to 1 face. You do this by selecting one such edge, and then doing

  • Select -> Select Similar -> Amount of Faces around an Edge.

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I don't think you'll get away with hitting F (to Fill) and Ctrl + T to triangulate the result. (as shown below)

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There are applications like MeshMixer that can do these tasks automatically, but I say this not as an endorsement - rather as an avenue to explore if you need to do this type of processing a lot. When you relinquish control to a program there's always a trade-off.

  • 1
    $\begingroup$ Thanks to yours and Duarte FarrajotaRamos answers, I now understood Blender is not meant to be a CAD tool. I tried to select interior faces as you illustrated. It didn't work. I am including the complete mandible here. If you can help me select interior faces then great! if not, I will have to switch to another software package. <img src="https://blend-exchange.giantcowfilms.com/embedImage.png?bid=3438" /> $\endgroup$
    – John
    Jun 23, 2017 at 3:39
  • $\begingroup$ In that file there are no detached interior cavities (unlike swiss cheese) , it's all one intricate surface with holes on the outer surface that lead to interior cavities. I can't think of any automated Blender tools that will make this task any easier (that doesn't mean there aren't any) . I'll update my answer $\endgroup$
    – zeffii
    Jun 23, 2017 at 7:51
  • $\begingroup$ I think you might be looking for a different tool, MeshMixer springs to mind. $\endgroup$
    – zeffii
    Jun 23, 2017 at 8:13
  • $\begingroup$ Thanks again. After I applied box select a few times all over the exterior, some how all polygons were ended up selected. So it didn't quite work out. Interesting solution though! $\endgroup$
    – John
    Jun 25, 2017 at 1:18
  • 1
    $\begingroup$ Thank you all I think I did it. Appreciate all the help. $\endgroup$
    – John
    Jul 2, 2017 at 1:40

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