CGAL users discussion list

[Sebastian Bachmann <>]

Hello,

I created an image meshing tool, similar to the one given here in this 
example code: 
https://doc.cgal.org/latest/Mesh_3/Mesh_3_2mesh_3D_image_with_features_8cpp-example.html 
with the only difference, that I extract the surface elements and not 
write the full 3D mesh.
I noticed, that on the image boundary, the vertices would be not exactly 
on the face but roughly +- the relative error bound given in 
create_labeled_image_mesh_domain. For examples, nodes on the xy plane at 
z=0 are not on z=0 but for example -0.01 to 0.01. While the protected 
polylines are exact and have always z=0.
I created for example a mesh from the 420.inr example with the same 
meshing criteria as given in the example and can see that behaviour there.

While you can control the maximal deviation using the relative error 
bound, there will always be some deviation. And if I set the relative 
error bound too low, it seems the meshing never finishes.
I wonder now, if it is possible to constraint the mesh (similar to the 
1d polylines), such that the vertices for facets on the image boundary, 
are always exactly on the image boundary?

Best,
Sebastian