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I've been trying to import a .gmsh mesh file into PreView (file here). However, when I try to import it as geometry, it says that it doesn't recognize the Entities section: "Unknown Section: Entities." If I delete the Entities section from the file, it then gives "Error while reading Nodes section." These two programs should be compatible, right?
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Hi,
It looks like this file is a newer version of the gmsh file format that PreView is not familiar with. I'll take a look at what's involved in supporting this version, but if you can export this file to an older gmsh (version 2) or a different file format, that might work too.
Cheers,
SteveDepartment of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of Utah -
I had to go back to the old gmsh version to do the meshing. However, I'm having some issues doing local mesh refinement on a thin spherical shell in gmsh, since I can't seem to create a mesh that is finer near a point on the surface of a sphere while also having a structured mesh with layers perpendicular to the sphere. Is there any way to refine a mesh locally (near a point) in PreView?Originally posted by maas View PostComment
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Hi,
There is a way to refine an element selection PreView. If you select an element near the point of interest, then that might work. This is how you do this:
1. Import a tetmesh.
2. Select an element near the point of interest.
3. Activate the mesh panel and click Tetgen
4. Set a desired element size, click "split facets" and set the feather to e.g. 5 (which sets the number of element levels used for creating a smooth transition between the refined region and the rest of the mesh). You'll have to play a bit with these parameters. If you don't like the refined mesh, click Edit\Undo first before trying new parameters.
Let me know if that worked for you.
Cheers,
SteveDepartment of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of UtahComment
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Can I do this with a mesh created in PreView? What if it is not a tet mesh?Comment
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Unfortunately, we only have local refinement algorithms for tet meshes, but it works with tet meshes created in PreView too.
Cheers,
SteveDepartment of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of UtahComment
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I don't see the place to set the "feather"? Also, it's weird: when I select a point on a sphere with a tet mesh and follow the process you mentioned, it affects other points on the sphere in a weird mesh refinement pattern.Comment
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Maybe you are using the "Refine Mesh" tool, not the Tetgen tool? (The "Refine Mesh" tool is a template based mesh refinement algorithm. Sometimes it can create streaks of additionally refined sections that are needed to resolve connectivity issues.) If you don't see the Tetgen option, perhaps first convert the model to an Editable Mesh. Then, on the Mesh panel tab, you should find the Tetgen tool, with the options mentioned above.
Cheers,
SteveDepartment of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of UtahComment
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I think I am using Tetgen. This is what I see (with nothing that mentions feathers):Originally posted by maas View Post
tetgen.JPGComment
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That's interesting. Are you using the most recent version of PreView? I checked our release version (which should be the one up on the web), and it has that feather option. So, perhaps try installing the latest version on the web and see if in that version the feather option appears.
SteveDepartment of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of UtahComment
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It does show up in the most recent version of PreView, although those streaks are still there.Comment
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The pattern is particularly strange when I try to refine an element in a thin sphere of finite thickness (using tetgen, obviously). It seems to try to refine the whole thing.Originally posted by maas View PostComment
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It occurred to me that Tetgen will also improve the mesh based on the quality criterion. It applies that to the whole mesh, even if you are only refining it locally. Try setting the "minimum radius-edge ratio" to a large value (e.g. 100) and see if that has any effect.
SteveDepartment of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of UtahComment
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No change, it still refines the whole thing. This is most noticeable on a thin sphere but there are those patterns of refined regions still on thicker or solid spheres.Comment
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Can you please send me your tet mesh. If it's too big to upload here, you may send it to steve dot maas at utah dot edu. I'll see if I can figure out what's going on.
SteveDepartment of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of UtahComment
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