CGAL users discussion list

[Andreas Fabri <>]

Hi Christian,

You might further investigate the surface mesher, as comparing it with
a marching cubes algorithm is comparing apples and pears. The surface
mesher will produce quality triangles, and you can have uniform sized
triangles or triangles with the size adapted to the curvature, that
is few triangles where the surface is flat, and many triangles where
you have high curvature.   So in order to have a fair comparison,
you should compare it to marching cubes followed by mesh simplification.

Obvioulsly if badly shaped triangles are not a problem for your use case,
the added value I try to point out, is not valuable for you.

Best regards,

andreas

Christian Walder wrote:
> I see, thanks. Can anyone recommend a good c++ implementation of the 
> marching cubes algorithm? I am quite surprised that this is not easier 
> to find...
>
> On Fri, Jul 17, 2009 at 11:09 AM, Mariette Yvinec 
> < 
> <mailto:>> wrote:
>
>     CGAL Surface mesher is not a marching cube.
>     It builds  iteratively a sampling adapted to the surface geometry
>     so that the restricted triangulation  of this sampling is
>     an accurate approximation of the surface and a nice
>     surface mesh formed with well shaped triangles.
>
>
>     Christian Walder wrote:
>
>         Dear All,
>
>         I have used the CGAL library to perform marching cubes on an
>         implicit surface. Unfortunately it is extremely slow -
>         previously I have used a different implementation from an
>         unknown author, and it is orders of magnitude faster for roughly
>         the same resolution. I am wondering if I have called the
>         functions correctly, and whether there are any easy ways attempt
>         to speed it up.
>
>         Best Regards,
>
>         Christian
>
>         ps.
>
>         The key snippet of code is the following:
>
>          Tr tr;            // 3D-Delaunay triangulation                
>                                                    C2t3 c2t3 (tr);   //
>         2D-complex in 3D-Delaunay triangulation                        
>                              Surface_3 surface(implicit_function,
>         Sphere_3(Point_3(center[0],center[1],center[2]), radius));
>          // defining meshing criteria                                  
>                                                  
>          CGAL::Surface_mesh_default_criteria_3<Tr> criteria(30.,  //
>         angular bound                                                  
>                                         radius_bound,  // radius bound  
>                                                                        
>                 distance_bound); // distance bound                  
>          CGAL::make_surface_mesh(c2t3, surface, criteria,
>         CGAL::Non_manifold_tag());
>          
>
>
>     -- 
>     Mariette Yvinec
>     Geometrica project team
>     INRIA  Sophia-Antipolis  
>
>
>     -- 
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