[vtkusers] normals

[Sylvain Jaume]

There is indeed a vtkDelaunay3D, but you will end up with tetrahedral
mesh while you need a surface mesh (made of triangles). I would suggest to
extract the triangles of the outer surface. I am not aware of a vtk filter
doing that, but I'm sure someone else in the vtk community could help you
with that.

One you've got your surface mesh, simply use vtkPolyDataNormals in the
following way:

vtkPolyDataNormals *PDnormals = vtkPolyDataNormals::New();
PDnormals->SetInput(yourMesh);
PDnormals->Update();

vtkNormals *normals = PDnormals->GetPointData()->GetNormals();

// then you can play around with the normals calling the method
// to get normal for vertex with index i
float *n = normals->GetNormal(i);

That's as simple as that! ;-)
Sylvain

On Tue, 8 May 2001, Nikita Kojekine AKA Kitya Karlson wrote:

> Thank you for your answer. I would like to define normal to a point from
> a point cloud as an average normal on triangles, I would get, If I connect by triangles this
> point and it's nearest neighboors. Is there a Delaunay triangulation for 3D in vtk, how can I use
> it and than get this normals?
> 
> > Hi Nikita,
> >
> > How do you define a normal for a point in a point cloud (vtkpoints)?
> > If you create a surface mesh (polydata) out of your point set, you could
> > use vtkPolyDataNormals and get the normals as pointdata attributes.
> >
> > Hope this helps
> > Sylvain
> >
> > On Mon, 7 May 2001, Nikita Kojekine AKA Kitya Karlson wrote:
> >
> > > Hello!
> > > I have a set of points vtkPoints, which represent the surface.
> > > Can I get for each point 2 points instead of it - one on -0.001 on
> > > normal
> > > from the original and one on +0.001? how can i get normal with vtk?
> > > Thank you.
> > >
> > >
> > >
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