[vtkusers] vtkConnectivityFilter

[SM Rolfe]

Thanks, I noticed when I viewed the mesh instead of the surface, that the
resolution had not actually changed, but as Cory suggested, the rendered
surface just appeared more faceted.

Recalculating the surface normals using vtkPolyDataNormals greatly improved
the appearance of the surface. Thanks again for your input.

On Mon, Oct 24, 2016 at 6:57 AM, David Thompson <david.thompson at kitware.com>
wrote:

> > Is the resolution really reduced, or does it just look more faceted
> because surface normals have been lost or modified? Try connecting a
> vtkPolyDataNormals filter after the vtkCleanPolyDataFilter if that is the
> case.
>
> I was thinking it might be because the vtkCleanPolyData filter averages
> point-scalar values used for coloring when it merges coincident vertices.
> That makes the mesh appear to lose resolution because it has... there are
> not as many unique points after coincident vertices are merged. Shy of
> perturbing coincident points and inserting lots of tiny little triangles to
> fill the gaps, I don't see a way to get around it and be left with a
> connected mesh.
>
>         David
>
> > On Sat, Oct 22, 2016 at 12:11 PM, SM Rolfe <smrolfe at uw.edu> wrote:
> > Hi David,
> > Thanks! The vtkCleanPolyData filter solves the connectivity issue. It
> also looks like it's reducing the resolution of the output mesh
> significantly. If it's only deleting the repeated points, I don't think
> this should be occurring?
> > Thanks,
> > Sara
> >
> > On Sat, Oct 22, 2016 at 5:36 AM, David Doria <daviddoria at gmail.com>
> wrote:
> > On Fri, Oct 21, 2016 at 10:42 PM, SM Rolfe <smrolfe at uw.edu> wrote:
> > Thanks David, I think you're right. When I try using the
> vtkDataSetSurfaceFilter or vtkExtractEdges I can get a connected surface,
> but it changes the original mesh points. Do you have any advice on the best
> way to correct the connectivity without altering these points? I am
> guessing I could go through each mesh point, look for repeats and add
> connectivity, but I'm wondering if there's a more efficient way?
> >
> > Thanks for your help,
> > Sara
> >
> > I think vtkCleanPolyData does that: http://www.vtk.org/Wiki/VTK/
> Examples/Cxx/PolyData/CleanPolyData
> >
> > David
> >
> >
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> >
> > --
> > Cory Quammen
> > Staff R&D Engineer
> > Kitware, Inc.
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