[vtkusers] Fwd: Re: Problem in Converting Lines to vtkPolyLine

[Nicolas Sarrasin]

Ok i've found the problem.

It comes from my convertion. (Sometimes I have to reverse the order of 
the new line to add...)

FYI I also use CleanPolyData before my convertion.

Thanks for our help, and sorry for disturbance ^^.

Nicolas.

Le 06/01/2011 15:10, David Gobbi a écrit :
> If vtkStripper works most of the time, but not all the time, it might 
> be a tolerance issue.  What I mean is, the endpoints for the line 
> segments might not match exactly.
>
> You could try using vtkCleanPolyData with SetTolerance(1e-6) before 
> vtkStripper.  This will merge all nearly-coincident points.
>
>   David
>
>
> On Thu, Jan 6, 2011 at 6:55 AM, Nicolas Sarrasin 
> <nsarrasin at phenix-systems.com <mailto:nsarrasin at phenix-systems.com>> 
> wrote:
>
>     Yes of course !
>
>     That's why I'm writing "For most of case it works well",
>     vtkStripper helps me a lot.
>
>     But with this example, my convertion fails.
>
>     With debug, I found that the secondth (and last) line close the
>     arc of circle but when I display it, this doesn't appear, as it's
>     shown in the pictures I linked.
>
>     Le 06/01/2011 14:47, David Gobbi a écrit :
>>     Hi Nicolas,
>>
>>     In my last email to you, I recommended the vtkStripper filter for
>>     generating a polyline from line segments.  Did you try it?
>>
>>     Cheers,
>>
>>         David
>>
>>
>>     On Thu, Jan 6, 2011 at 3:30 AM, Nicolas Sarrasin
>>     <nsarrasin at phenix-systems.com>  <mailto:nsarrasin at phenix-systems.com>  wrote:
>>>     Hi all,
>>>     I'm trying to convert a set of line into one only vtkPolyLine. (original
>>>     post here :
>>>     http://vtk.1045678.n5.nabble.com/construct-a-vtkPolyLine-PolyGon-from-a-set-of-vtkLines-td3325716.html)
>>>
>>>     I go through all the polylines of vtkPolyData->GetLines() and then get the
>>>     associated points.
>>>     For most of case it works well, but I'm actually encounter a problem on a
>>>     case.
>>>
>>>     The input polydata
>>>     (http://img525.imageshack.us/img525/8370/vtkconvertioninit.png) is composed
>>>     of two lines which trace an arc of circle.
>>>     After the convertion, this arc is closed
>>>     (http://img502.imageshack.us/img502/8773/vtkconvertionres.png).
>>>     It comes from the second line which might not be correct.
>>>
>>>     Can someone explain me what is going wrong ?
>>>
>>>     Thanks by advance.
>>>
>>>     Here is a c++ sample code with the input file attached (wire.vtp).
>>>     ****
>>>     #include<vtkSmartPointer.h>
>>>     #include<vtkCellArray.h>
>>>     #include<vtkPoints.h>
>>>     #include<vtkPolyData.h>
>>>     #include<vtkXMLPolyDataReader.h>
>>>     #include<vtkXMLPolyDataWriter.h>
>>>     #include<vtkPolyLine.h>#include<vtkSmartPointer.h>
>>>     #include<vtkCellArray.h>
>>>     #include<vtkPoints.h>
>>>     #include<vtkPolyData.h>
>>>     #include<vtkXMLPolyDataReader.h>
>>>     #include<vtkXMLPolyDataWriter.h>
>>>     #include<vtkPolyLine.h>
>>>
>>>     int main (int argc, char *argv[])
>>>     {
>>>          vtkSmartPointer<vtkXMLPolyDataReader>  reader =
>>>     vtkSmartPointer<vtkXMLPolyDataReader>::New();
>>>          reader->SetFileName("./wire.vtp");
>>>
>>>          vtkSmartPointer<vtkPolyData>  init_data =
>>>     vtkSmartPointer<vtkPolyData>::New();
>>>          init_data = reader->GetOutput();
>>>
>>>          vtkSmartPointer<vtkPoints>  init_points =
>>>     vtkSmartPointer<vtkPoints>::New();
>>>          init_points=init_data->GetPoints();
>>>
>>>          vtkSmartPointer<vtkCellArray>  init_lineArray =
>>>     vtkSmartPointer<vtkCellArray>::New();
>>>          init_lineArray = init_data->GetLines();
>>>
>>>          int nblines = init_lineArray->GetNumberOfCells();
>>>
>>>          vtkSmartPointer<vtkPolyData>  new_data =
>>>     vtkSmartPointer<vtkPolyData>::New();
>>>          vtkSmartPointer<vtkPoints>  new_points =
>>>     vtkSmartPointer<vtkPoints>::New();
>>>          vtkSmartPointer<vtkPolyLine>  polyline =
>>>     vtkSmartPointer<vtkPolyLine>::New();
>>>          vtkSmartPointer<vtkCellArray>  new_lineArray =
>>>     vtkSmartPointer<vtkCellArray>::New();
>>>
>>>          double coords[3];
>>>          vtkIdType nbpts=0, *pts=0;
>>>          for( init_lineArray->InitTraversal(); init_lineArray->GetNextCell(nbpts,
>>>     pts);)
>>>          {
>>>              vtkIdType init_ind=0, new_ind=0;
>>>              for(int p=0; p<nbpts; p++)
>>>              {
>>>                  init_ind=pts[p];
>>>                  if(init_ind<0)
>>>                      continue;
>>>                  init_points->GetPoint( init_ind, coords);
>>>
>>>                  new_ind=new_points->InsertNextPoint(coords);
>>>                  polyline->GetPointIds()->InsertNextId(new_ind);
>>>              }
>>>          }
>>>          new_lineArray->InsertNextCell(polyline);
>>>          new_data->SetPoints(new_points);
>>>          new_data->SetLines(new_lineArray);
>>>
>>>          vtkSmartPointer<vtkXMLPolyDataWriter>  writer =
>>>     vtkSmartPointer<vtkXMLPolyDataWriter>::New();
>>>          writer->SetFileName("./new_wire.vtp");
>>>          writer->SetInput(new_data);
>>>          writer->Write();
>>>     ****
>
>
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