CGAL users discussion list

[Sebastien Loriot <>]

Do you observe this behavior on all images or only a specific one?
For example, when using 420.inr do you have such an issue?

What could case such an over refinement (provided you are not using 
master version of CGAL) is if the mesher is trying to respect some
topological criteria (a very tiny handle for example, but that would be 
surprising in an image).

Best,

Sebastien.

On 5/24/23 14:14, Sebastian Bachmann ( via cgal-discuss 
Mailing List) wrote:
> Hi everyone,
>
> I have an image from which I want to create a coarse surface mesh.
> The code I use for that is based upon the example 
> mesh_3D_image_with_features.cpp, however it is adopted to then extract 
> the surface and write an OFF file: 
> https://gist.github.com/reox/0df1f446f0ff9d46e0688b60e8e858b8
>
> As you can see, the Mesh_criteria is set to a really coarse mesh. The 
> input image (attached) I use has a voxel size of around 0.5mm and 
> represents a proximal femur.
> Now, for some reason, I get extremely fine triangle elements in certain 
> places (see attached image).
>
> I find that peculiar, as the facet_distance is already quite large, and 
> I thought that this might be the main issue here. I remembered, that 
> also the relative_error_bound in the create_labeled_image_mesh_domain 
> can have an influence, but reducing this rather creates a "spiky" mesh 
> than removing those small elements. (Eventually when it is set to 0.1, 
> the small elements vanish, but then the vertices are all over the place 
> and not on the isosurface anymore...)
>
> Is there anything I missed here, maybe did I use wrong parameters? Or is 
> there another way how I could produce such coarse meshes?
>
> Best,
> Sebastian