[Gmsh] Remesh STL with constraint on edge length / area

[Christophe Geuzaine]

On 09 Aug 2012, at 15:59, Domingo Chavez <azrael3000 at gmx.net> wrote:

> Dear all,
> 
> I have the following problem that I'm trying to solve:
> 
> The input file is an STL file, which I can load into gmsh without problems following tutorial # 13.
> Next I want to remesh the geometry, which is an open skin-mesh such that:
> 1.) Edge length < threshold1
> 2.) Triangle area < threshold2
> 
> From what I understand I should be able to use Fields to obtain this. However, I was not able to figure out how to set the edge length / triangle area as field.
> 

Hi Arno - There is no criterion in Gmsh that allows to set the edge length / triangle area. Using the (isotropic) Frontal algorithm you will get triangles as close as possible to equilateral, with edge lengths prescribed by the mesh size field.

> Another issue is the meshing itself. I saw that the points are on the surface but the edges that are created are not necessarily part of the surface. This results in some smoothing of corners, which ideally, I'd like to avoid.
> 

If you want to preserve sharp edges, you have to explicitly define them. That's why in tutorial/t13.geo we define several "Compound Surfaces", bounded by compound lines.

If you start from an unclassified STL mesh, you can use the "Mesh->Reclassify 2D" tool to automatically split the STL into patches depending on some angle threshold between adjacent triangles.

Cheers,

Christophe


> Thanks in advance for your help.
> 
> Best regards,
> Arno
> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine