[vtkusers] simple question vtkCleanPolyData

[Amy Squillacote]

Hi Jean-Do,

No, there is not a filter in VTK to only remove duplicate points in a 
dataset with no cells.  One thing you could do is to add a vtkVertex 
cell per point in your dataset.  Then if you pass this new dataset 
through vtkCleanPolyData, duplicate points will be merged, but you 
won't have the problem of points being removed because they are not 
being used by a cell.

- Amy

At 02:47 AM 4/18/2006, jeando.barnichon at free.fr wrote:
>Ok, I understand.
>The next question now is :
>Is there a filter that could do the "simple" task of "cleaning" (i.e. removing
>duplicate points) a polydata that is made of points only?
>Jean-Do
>
>Selon Amy Squillacote <amy.squillacote at kitware.com>:
>
> > You are right; you do need cells in your vtkPolyData, not just
> > points.  This is because one of the features of vtkCleanPolyData is
> > to remove points that are not used by any cells.  Thus if your data
> > has no cells, then this is true for all the points in your data set,
> > so all of them will be removed, resulting in an empty vtkPolyData data set.
> >
> > - Amy
> >
> > At 05:06 PM 4/17/2006, Janet Kim wrote:
> > >I tried out vtkCleanPolyData and it looked like you
> > >might need actual geometry for the polydata to clean,
> > >not just points.  When I just had points, I had the
> > >same result.  But once I added the points to cells,
> > >the clean worked.  Maybe someone else can explain a
> > >bit better, unless, I'm wrong.
> > >
> > >
> > >On Mon, 17 Apr 2006, Jean-Dominique Barnichon wrote:
> > >
> > >>Should be a simple one.
> > >>I've got a polydata containing only points (see end of email), some
> > >>of which are duplicate points.
> > >>I want to keep only a single point with given coordinates (yes, I
> > >>know that the vtkCleanPolyData filter should do the trick, but I
> > >>just can couldn't get it working so far).
> > >>When I run the piece of code given below, the cleaned polydata is
> > >>empty (i.e. it has 0 points), and I don't understand why.
> > >>Any Idea?
> > >>Jean-Do
> > >>
> > >>Code snippet:
> > >>       vtkPolyDataReader *re = vtkPolyDataReader::New();
> > >>       re->SetFileName("InitialPolydata.vtk");
> > >>
> > >>       vtkPolyData *pdata = vtkPolyData::New();
> > >>       pdata = re->GetOutput();
> > >>
> > >>       // pdata is the vtkPolyData
> > >>       vtkCleanPolyData *Clean = vtkCleanPolyData::New();
> > >>       Clean->SetInput(pdata);
> > >>       Clean->SetTolerance(0.0);
> > >>       Clean->PointMergingOn();
> > >>       Clean->Update();
> > >>
> > >>       vtkPolyDataWriter *wr = vtkPolyDataWriter::New();
> > >>       wr->SetFileName("CleanedPolydata.vtk");
> > >>       wr->SetInput(Clean->GetOutput());
> > >>       wr->Write();
> > >>
> > >>
> > >>//beginning_of_file (InitialPolydata.vtk)
> > >># vtk DataFile Version 3.0
> > >>vtk output
> > >>ASCII
> > >>DATASET POLYDATA
> > >>POINTS 12 float
> > >>3.35936 1.84257 49.9219 6.3551 1.84257 40.9347 17.8945 1.84257 39.9079
> > >>17.8945 1.84257 39.9079 25.3551 1.84257 23.6583 25.3551 1.84257 23.6583
> > >>34.0223 1.84257 20.6629 34.0223 1.84257 20.6629 36.8945 1.84257 20.1843
> > >>45.263 1.84257 1.84257 45.263 1.84257 1.84257 83.3594 1.84257 0
> > >>
> > >>POINT_DATA 12
> > >>//end_of_file
> > >>
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