# Make stl into solid and smooth surface

**URL:** <https://discourse.slicer.org/t/make-stl-into-solid-and-smooth-surface/15515>\
**Category:** Support\
**Created:** [January 14, 2021, 2:22am UTC](https://discourse.slicer.org/t/make-stl-into-solid-and-smooth-surface/15515 "2021-01-14T02:22:12Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Valentina\_Mejia\_Gall](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/valentina_mejia_gall/32/8759_2.png) [@Valentina\_Mejia\_Gall](https://discourse.slicer.org/u/Valentina_Mejia_Gall)\
**Post date:** [January 14, 2021, 2:22am UTC](https://discourse.slicer.org/t/make-stl-into-solid-and-smooth-surface/15515/1 "2021-01-14T02:22:12Z")

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I need to do a finite element analysis, for this I export the STL and I have a surface with several faces or triangles, I need to convert it to solid and the surface is as “smooth” as possible. is there any way to do it in 3D-slicer

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [January 14, 2021, 2:32am UTC](https://discourse.slicer.org/t/make-stl-into-solid-and-smooth-surface/15515/2 "2021-01-14T02:32:34Z")

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You can use [SegmentMesher extension](https://github.com/lassoan/SlicerSegmentMesher#segment-mesher-extension) to created a smoothed volumetric mesh, readily usable for finite element analysis.

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**Author:** ![Valentina\_Mejia\_Gall](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/valentina_mejia_gall/32/8759_2.png) [@Valentina\_Mejia\_Gall](https://discourse.slicer.org/u/Valentina_Mejia_Gall)\
**Post date:** [January 15, 2021, 12:13am UTC](https://discourse.slicer.org/t/make-stl-into-solid-and-smooth-surface/15515/3 "2021-01-15T00:13:37Z")

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I do it as the tutorial said but I have multiple question.

I need to do a finite element analysis with this model

 ![Screen Shot 2021-01-14 at 7.05.47 PM](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/3/6/362c6ac734d00da212a0d5868d5856fac0b96e41.png)

But when I do as the tutorial said, first when i have to select the segmentation its appear as segmentation 1,2,etc. So i dont know exactly which one is the tibia,fibula, etc as i have them label in the segmentation.

 ![Screen Shot 2021-01-14 at 7.01.48 PM](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/7/97aad8b00f486f3c105bb4d20d1f037191a3c682.png)

Then when i see the final result, it’s a bit chaotic, the both fibulas have been cut in half, and is not as smooth as i would like to. Is there a way to fix that?

 ![Screen Shot 2021-01-14 at 7.03.17 PM](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/2/f/2fb2c6bef1b51e049df0841e00d97a852bbd1c85.png)

Thanks a lot for the help.  
I am basing myself on this program in which they do it directly and apply a smooth and the mesh looks and that’s what I’m aiming to have.

[![](https://img.youtube.com/vi/HJmWc_-_BrU/maxresdefault.jpg "How to Mesh a 3D Model | Mimics Innovation Suite") ](https://www.youtube.com/watch?v=HJmWc_-_BrU&t=101s)

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [January 15, 2021, 2:01am UTC](https://discourse.slicer.org/t/make-stl-into-solid-and-smooth-surface/15515/4 "2021-01-15T02:01:09Z")

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Default mesh element size is very large so that you start from a quickly generated low-resolution mesh. You need to adjust meshing parameters to fulfill your needs (details, smoothness, number of cells, etc.). These [parameter descriptions](https://github.com/lassoan/SlicerSegmentMesher#mesh-generation-parameters) should help, but if something is not clear then let us know.

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**Author:** ![Valentina\_Mejia\_Gall](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/valentina_mejia_gall/32/8759_2.png) [@Valentina\_Mejia\_Gall](https://discourse.slicer.org/u/Valentina_Mejia_Gall)\
**Post date:** [January 19, 2021, 2:29am UTC](https://discourse.slicer.org/t/make-stl-into-solid-and-smooth-surface/15515/5 "2021-01-19T02:29:24Z")

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Hello Andras,  
I have a question, searching in the forum I came across this article about how to save and convert the vkt file into a volumetric mesh, but I don’t know how to manipulate 3dSlicer with code.  
Is there a program or a tutorial on how to do that process?

Article

> [@Convert a surface mesh to a volumetric mesh in 3D Slicer](https://discourse.slicer.org/t/convert-a-surface-mesh-to-a-volumetric-mesh-in-3d-slicer/1416/10):
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> ICEM can import surface meshes (STL files) - see for example [this](https://www.cfd-online.com/Forums/ansys-meshing/77427-meshing-stl-surface-icem.html) old forum topic. Segment Mesher can generate tetrahedral meshes that you can save in VTK unstructured grid (.vtu) file format. You may need a mesh conversion utility to convert it to a file format that can be read by your FEM software.