CGAL users discussion list

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

Le Monday 22 August 2016 14:04:36 Joan Hensen a écrit :
> Hey guys,
> 
> I'm using the example Surface_mesher/mesh_a_3d_gray_image.cpp in order to
> triangulate a 3D image.
> 
> Currently, I have a grey level image with several objects in it. Larger and
> smaller ones. When I try to apply 'mesh_a_3d_gray_image' on it some of the
> smaller objects near the image border are missing in the resulting mesh. Is
> this example only applicable if the image contains only the iso-contour of
> one single object or can I achive to get meshes for all of them? If yes,
> how :-)?

Hi,

The way the mesh generator engine discovers the mesh domain does not 
guarantee 
to mesh all the connected components of the mesh domain, even if the meshing 
parameters are small enough.

The process can be helped by a custom generation of the initial 
triangulation. 
In CGAL-4.9-beta1, I have added an example that uses a custom initialization 
to ensure that the initial triangulation will have vertices on all connected 
components of the input. That example is

  CGAL-4.9-beta1/examples/Mesh_3/mesh_3D_image_with_custom_initialization.cpp


As the code of that custom initialization is non-trivial, that code was 
extracted to non-documented header files. You can find all the details in the 
documentation for CGAL-4.9, section "Domains From Segmented 3D Images, with a 
Custom Initialization":

  http://doc.cgal.org/4.9/Mesh_3/#title24

and in the the pull-request on Github:

  https://github.com/CGAL/cgal/pull/1115



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