[vtkusers] coincident points in grid

[Kent Eschenberg]

The question is too vague. Lets consider cells that fit together to form a 
smooth, curved surface. Lets assume you do not provide vertex normals and let 
VTK calculate them. Lets assume your visualization is a Gouraud-shaded view of 
this surface.

I think the surface in (1) would be faceted because the algorithm cannot tell 
that the cells are adjacent and that the vertexes are shared. I think the 
surface in (2) would be smooth.

Try it and let us know.
Kent
Pittsburgh Supercomputing Center

Martin Baumann wrote:
> Hi,
> 
> I have a question concerning the usage of points in cells. I build two
> unstructured
> grids that should represent the same scene, but two different strategies:
> 
> (1) Each point id is used in one cell only. So for a point in space that
> is vertex
> for more than one cell must exist more than one representations of that
> point
> (=> several point ids for the same point in space).
> 
> (2) Each point in space that is used as a vertex is represented by one
> unique
> point id.
> 
> Making sure that in case (1) the point data is the same for all points
> that are
> placed at the same point in space , the visualization of (1) and (2) seem to
> be the same. Of cause in case (1) more data has to be stored.
> 
> Does the use of more than one point id for one point in space affect the
> visualization in any sense? Should case (1) be avoided for some reason?
> 
> Best regards,
> M.B.
> 
> 
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-- 
Kent Eschenberg  eschenbe at psc.edu  (412)268-6829
Scientific Visualization Specialist
Pittsburgh Supercomputing Center, Pittsburgh, PA

Why did the chicken cross the mobius strip?