Can you send the 2 STLs (I don't see them in the zip)?
Christophe
> On 1 Nov 2019, at 11:30, MA Ariza-Gracia <miguel.ar...@artorg.unibe.ch> wrote:
>
> Dear Dr Geuzaine, Dr Remacle, and the Gmsh community,
>
> first of all, thank you for sharing the software with us! I'm a postdoc
> working (mostly) in optics and I need to reconstruct some free-shape surfaces.
>
> My final goal is to create a volume mesh enclosed by two discrete STL
> surfaces (given by a point cloud). The pipeline to do so is as follows:
> 1) Read point clouds and triangulate using Delaunay (scipy.spatial)
>
> 2) Create a 2 discrete surfaces giving the node coordinates and the
> connectivity of the triangles
>
> 3) Create a volume using a surface loop on both surfaces
>
> 4) Mesh the volume
>
> 5) Exporting the mesh to Abaqus/LS-Dyna (whatever software)
>
>
>
> After reading the manual, tutorials and mailing list, the only approached
> that worked was the next one: having a single closed shell joining 'manually'
> the nodes in the boundary. I say manually because I needed to implement the
> substitution of the nodes myself and I couldn't do it using Gmsh using
> removeDuplicate and so on (i.e., I didn't know how to do it). After having a
> single closed shell without duplicate nodes and with the normals pointing
> outwards, I manage to mesh the volume inside the models (see
> manually-merged-thick.msh and manually-merged-thin.msh).
>
>
>
> However, as this is my first approach to Gmsh, this is not efficient and I
> would like to know if:
>
> 1) There is a more efficient procedure to, given two different STLs, mesh the
> volume enclosed by the two of them (as I said, I tried may approaches
> including the ones regarding Earth topology reconstruction in the mail list,
> but I couldn't find a proper solution).
>
> 2) There is a way of both remeshing the STLs AND meshing the volume at the
> same time. In one of the approaches, I parameterized the discrete STL
> surfaces with classifySurfaces and createGeometry (see the Jupyter notebook,
> three first attempts). This allowed me to re-mesh the STL surfaces but,
> unfortunately, I could not mesh the volume after (complaining about 0
> elements in the volume). As my Delaunay triangulation is quite ugly, this
> would be my preferred option if you could give me a hint on how to proceed.
>
> 3) In the end, I will have two surfaces: one main surface with one inclusion
> inside itself. From what I've read, I know I cannot do Boolean operations (as
> I'm using meshes and discrete elements), so I would appreciate any hint on
> how to proceed in this regard.
>
>
>
> Files enclosed in compressed folder 'inquiry-gmsh.zip':
>
> • try-inquiry.ipynb: Jupyter notebook with the API code to create the
> surfaces
> • {anterior-lenticle-surface.txt, posterior-lenticle-surface.txt}:
> files containing the Cartesian point cloud
> • After running the code, it will generate:
> • thin-1.stl, thin-2.stl: surfaces used to generate the
> convex-convex thin lens
> • surface-1.stl, surface-2.stl: surfaces used to generate the
> concave-convex thick lens
> • shell-thin-lens.msh: attempt to mesh the volume of the thin
> mesh using: i) Two different STL surfaces (gmsh.merge); ii) remove duplicate
> coincident nodes (gmsh.removeDuplicateNodes); and iii) re-parameterizing
> • shell-concave2convex.msh: attempt to do the same as the
> previous one but with the thick lens (-> discard problems with sharp edges in
> the periphery)
> • merged-shell-concave2convex.msh: attempt to mesh the volume
> of the thick lens using: i) One single STL surface with duplicated nodes in
> the boundary; ii) Remove duplicated nodes using removeDuplicateNodes; iii)
> and classify surfaces + creating geometry
> • manually-merged-thick.msh and manually-merged-thin.msh:
> success BUT: i) I needed to remove myself the duplicated nodes; ii) If I try
> to parameterize the surface, I cannot mesh the volume inside but only the
> surfaces.
>
>
> Versions used:
>
>
> - Ubuntu 18.04
>
> - Gmsh 4.4.1 through the implementation in conda-forge
>
> - Python 3.7 with Anaconda
>
>
>
> Best regards,
>
>
> MA
>
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—
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine
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