[vtkusers] Dark triangles in Delaunay triangulation (.ply)

[Kevin H. Hobbs]

On 10/19/2011 11:35 AM, antbar wrote:
> 
> To Kevin:
> 
> Yes, I set an alpha value beacuse if I do not, final triangulation is very
> bad. I´m a begginer in this topic so I don´t understand what you mean
> 
> Thanks, I keep trying
> 

With alpha set you get a mix of tetrahedra, triangles, lines, and vertex
cells, and the normals often look very bad.

With alpha set or set to zero, the 3D delaunay "triangulation" will
produce a complete "triangulation." I use the quotes because the cells
will be all tetrahedra. From what I've seen the normals look much
better, but the complete triangulation means all your points look like
they've been shrink wrapped.

You can use the tessellation filter to break the tetrahedra into
triangles, or the surface filter to get just the 2D cells on the
outside. Then you can get the size of each cell and discard the cells
that are too big. Which is what the alpha value would have done.

Unfortunately I don't see a quick and easy way (filter) to get the
length of each cell...

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