Happy new year!

Problem explanation

I am trying to modify a STL model generated by a CT scan (skin model), in order to close the surface. I am using this in brain simulations and in order to add electrodes on the skin surface, the surface shall be closed, otherwise the Mesh2EEG algorithm does not work. You can check my work here.

Unfortunately I can not share the CAD file here since it is under license agreement from the IT'IS foundation.

I have some screenshots below to give you the context of what I am trying to do.

This screenshot shows the model as is: 3D human head model

This screenshot shows the desired result of a closed base: 3D human head model with base closed

Also, ideally I would like to close the holes that are here and there on the surface as you can see from the screenshots.

Tested so far

  • I have tried to use meshlab with different filters, like close holes, remeshing, fixing, but none worked. I found some tips here and there but none worked.
  • I created a solid cube, and tried to subtract, but I did not have any luck there

Can you help me on that?

Thank you!

  • $\begingroup$ I think it fails becaused your mesh already has thickness, adding faces there would make the whole mesh non-manifold. I would add a plane with a small thickness, position it on the base of the head with overlap, and make a boolean union with it. Then manually remove the remaining vertices. Would that work ? $\endgroup$
    – Gorgious
    Commented Jan 9, 2021 at 10:16
  • $\begingroup$ I think the bisect tool in blender should do the work. You'll have to remove the inner layer, but then with select boundary loop, you should be able to close the mesh. $\endgroup$
    – Carlo
    Commented Jan 9, 2021 at 10:34
  • $\begingroup$ Thank you for the info! I did it with the knife tool and actually separated the surface in two objects, deleting the small one created with the knife tool, and then I selected the loop that was created, hit F, CTRL + T and there we go. $\endgroup$
    – dimst23
    Commented Jan 19, 2021 at 17:43
  • $\begingroup$ If you have found a solution, then please write an answer in the answer section below. Future users may benefit from it... $\endgroup$
    – Timaroberts
    Commented Jan 19, 2021 at 17:54

1 Answer 1


Update 19/01/2021 (Solution)

I finally found a way to this by using the knife tool. After searching I found this video which had exactly what I needed. The info from @Gorgious and @Carlo in the comments helped me get a better direction. In short the process is the following:

  • Use the knife tool
  • Create a cut, just above the end, to have different surfaces
  • Following the instructions of the video, to rip the selection and then separate the meshes, delete the small object at the base of the head.

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