Adding normals to a points cloud (for Poisson reconstruction)

[stla]

Hello,

Thanks to @sloriot I finally managed to do my first CGAL Poisson reconstruction. Here is my Poisson reconstructed solid Möbius strip:

Well, I was wondering something: if you don't have some normals, how do you compute them? I'm personally using the R package Rvcg to do that, a wrapper of the VCG C++ library. Is there such a functionality in CGAL? That would be nice.

[sloriot]

You can use CGAL::jet_estimate_normals() to estimate normal directions followed by
CGAL::mst_orient_normals() to estimate normal orientations

[stla]

Thanks! I found this example and I'm currently doing the implementation. At first glance the results look quite different from the ones of (R)vcg.

[stla]

It works! Here is the Poisson reconstructed solid Möbius strip with the VCG normals and with the CGAL normals. Hard to see any difference.

[sloriot]

Could you share the meshes? It seems that the one generated using CGAL normals is less smooth on the bottom part of the picture. If you also have the points set with normals if might be interesting to compare (You can use that function).

[stla]

Hello @sloriot ,

Which format do you want for the meshes?

[sloriot]

what ever works for you. The easier is std::ofstream("out.off") << std::setprecision(17) << poly;

[stla]

Ok, will try. Here is another example. Indeed, the mesh is smoother with the VCG normals (yellow).

[stla]

Here are the files. These are the files for the toroidal helix, not for the solid Möbius strip, I choosed these ones because the difference is more striking.

NB: The off.txt files actually are off files. Github does not accept them, so I added the txt suffix.

original_mesh.txt
out_VCGnormals.off.txt
out_CGALnormals.off.txt

[sloriot]

it is in original_mesh.txt

[sloriot]

together with CGAL and VCG normals

[sloriot]

will shortly create a gist with files readable in the polyhedron demo

[sloriot]

https://gist.github.com/sloriot/ed7df61ca280a003ce0896458df7fb16

[sloriot]

Thanks for the file!