[vtkusers] Filter to merge several lines into a single polyline?

Tue May 11 17:47:49 EDT 2004

Jean-Dominique,

	My mistake, I could reproduce your bug with a smaller data set, seems 
like vtkStripper is discarding polylines. I'll investigate, thanks for 
bug report.

Mathieu

# vtk DataFile Version 3.0
vtk output
ASCII
DATASET POLYDATA
POINTS 4 float
0 0 0
1 0 0
2 0 0
1 1 0
LINES 2 7
3 0 1 2
2 2 3

CELL_DATA 2
POINT_DATA 4


Jean-Dominique Barnichon wrote:
> Mathieu,
> 
> replacing
> 	LinePoly->SetLines((cutStrips->GetOutput())->GetLines());
> by
> 	LinePoly->SetPolys(cutStrips->GetOutput()->GetLines());
> 
> doesn't do what I need : it build a closed polyline, which is not what I
> expect as the 3D surface I am cutting through is not closed (it's a portion
> of a digitized topographic map).
> So in other word, I do expect an unclosed polyline as a result of the
> cutting operation.
> 
> Jean-Do
> 
> -----Message d'origine-----
> De : Mathieu Malaterre [mailto:mathieu.malaterre at kitware.com]
> Envoye : mardi 11 mai 2004 22:46
> A : Jean-Dominique Barnichon
> Cc : vtkusers
> Objet : Re: [vtkusers] Filter to merge several lines into a single
> polyline?
> 
> 
> Jean-Dominique,
> 
> 	Change:
> 
> LinePoly->SetLines((cutStrips->GetOutput())->GetLines());
> 
> into
> 
> LinePoly->SetPolys(cutStrips->GetOutput()->GetLines());
> 
> HTH
> Mathieu
> 
> Jean-Dominique Barnichon wrote:
> 
>>It's done already (see code of original message)
>>Jean-Do
>>
>>-----Message d'origine-----
>>De : Amy Henderson [mailto:amy.henderson at kitware.com]
>>Envoye : mardi 11 mai 2004 22:09
>>A : Jean-Dominique Barnichon; vtkusers
>>Objet : Re: [vtkusers] Filter to merge several lines into a single
>>polyline?
>>
>>
>>Hi Jean-Do,
>>
>>Try passing the results of vtkCutter through vtkStripper.
>>
>>- Amy
>>
>>At 04:04 PM 5/11/2004, Jean-Dominique Barnichon wrote:
>>
>>
>>>Hello,
>>>
>>>As a result of applying a vtkCutter filter to a 3D surface (see code
>>
>>snippet
>>
>>
>>>below), I obtain a vtkPolyData object that is made of :
>>>- a set of points,
>>>- a set of lines (7 in the example below, see ouput below).
>>>
>>>You can notice that output lines share end points, i.e. they could
> 
> 'easily'
> 
>>>all be converted into a single polyline (in the exmaple shown below, this
>>>could be done starting backward from the last line, but I don't known this
>>>can always be done this way).
>>>
>>>All I need is converting this set of 'jointive' lines into a single
>>>polyline.
>>>Is there any filter that can do that? Or do I have to write one by myself?
>>>
>>>Any answer/hint is welcome.
>>>Note that applying vtkCleanPolyData is pointless here as there are already
>>>no duplicate points.
>>>
>>>Jean-Do
>>>
>>>
>>>code snippet
>>>       //Define cutting plane
>>>       vtkPlane* plane = vtkPlane::New();
>>>       plane->SetOrigin(300., 500., 0);
>>>       plane->SetNormal(-1, -1, 0);
>>>
>>>       //Generate cut lines
>>>       vtkCutter* cutEdges = vtkCutter::New();
>>>       cutEdges->SetInput(Normals->GetOutput());
>>>       cutEdges->SetCutFunction(plane);
>>>
>>>       //Forms lines from cutter
>>>       vtkStripper* cutStrips = vtkStripper::New();
>>>       cutStrips->SetInput(cutEdges->GetOutput());
>>>       cutStrips->Update();
>>>
>>>       //Defines polygons as polyline
>>>       vtkPolyData* LinePoly = vtkPolyData::New();
>>>       LinePoly->SetPoints((cutStrips->GetOutput())->GetPoints());
>>>       LinePoly->SetLines((cutStrips->GetOutput())->GetLines());
>>>
>>>       //Write PolyData to file
>>>       vtkPolyDataWriter* wr = vtkPolyDataWriter::New();
>>>       wr->SetFileName("Line4.vtk");
>>>       wr->SetInput(LinePoly);
>>>       wr->Write();
>>>
>>>Output of the vtkPolyDataWriter (file Line4.vtk)
>>># vtk DataFile Version 3.0
>>>vtk output
>>>ASCII
>>>DATASET POLYDATA
>>>POINTS 28 float
>>>252.329 547.171 500 235.668 563.832 500 314.825 484.675 549.214
>>>305.908 493.592 553.277 224.208 575.292 500 223.112 576.388 500
>>>342.103 457.397 590.352 339.985 459.515 587.917 446.203 353.297 737.623
>>>441.629 357.871 700 294.445 505.055 542.116 343.253 456.247 592.317
>>>415.885 383.615 664.838 409.217 390.283 664.838 350.938 448.562 600
>>>426.08 373.42 670.902 439.236 360.264 700 492.288 307.212 866.422
>>>482.154 317.346 884.873 458.735 340.765 779.183 451.048 348.452 750.164
>>>479.711 319.789 887.034 463.563 335.937 800 512.234 287.266 900
>>>510.437 289.063 900 496.357 303.143 851.732 502.247 297.253 829.042
>>>519.514 279.986 900
>>>LINES 7 41
>>>4 0 1 4 5
>>>4 2 3 10 0
>>>3 6 7 2
>>>9 8 9 16 15 12 13 14 11 6
>>>7 17 18 21 22 19 20 8
>>>5 23 24 26 25 17
>>>2 27 23
>>>
>>>CELL_DATA 7
>>>POINT_DATA 28
>>>
>>>
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>>
>>
>>
>>
>>
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