CGAL users discussion list

["Laurent Rineau (CGAL/GeometryFactory)" <>]

Le Tuesday, June 5, 2018 7:47:50 PM CEST Zesen Qian a écrit :
> Hi list,
> 
> I have several question about Mesh_3.
> 
> 1. I'm generating isosurface by implicit function. It requires that
> the center of the sphere be inside of the mesh. The question is, given
> an arbitrary mesh, how can I find such a point?

Hi,

You talk at the same time about an implicit function and a mesh. What is 
actually your input?

> 2. Due to the first problem(I guess), the mesher seems to be sampling
> a lot at a specific spot on the surface, making the mesh very dense at
> that spot. While the generated mesh is self-intersection free by
> construction, the exported .off is not(because of the precision
> issue). I have set the precision to 17-digits and it doesn't help. I
> guess one approach is to give a lower bound on the facet_size, but I
> coudln't find such a parameter. Another approach is to simplify the
> mesh, but I'm worried this might lose some details of the mesh.

That is probably related. The default initialization of the mesh is done by 
shooting random ray around a point (and that point is the center of the 
sphere by default). If that point is close to the iso-surface, then ray 
shootings will produces initial points that are very close.

-- 
Laurent Rineau, PhD
R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
Release Manager of the CGAL Project       http://www.cgal.org/