[vtkusers] vtkMarchingSquares to vtkContourWidget

Nicolas Rannou nicolas_rannou at hms.harvard.edu
Wed May 5 18:26:24 EDT 2010


Hello,

I'm trying to extract contours using marching squares then to use this 
contour to initialize a vtkContourWidget.
But I couldn't get good results yet.

What I do:

/***************************************************************************/

vtkMarchingSquares* contours = vtkMarchingSquares::New();
contours->SetInput( image );
contours->GenerateValues ( 1, 0, 0 );

vtkStripper * stripper = vtkStripper::New();
stripper->SetInput( contours->GetOutput() );
stripper->Update();

vtkPolyData* testPolyD = vtkPolyData::New();
testPolyD->SetPoints( stripper->GetOutput()->GetPoints() );

vtkTransform *t = vtkTransform::New();
t->Translate( seed_pos[0], seed_pos[1], seed_pos[2] );

vtkTransformPolyDataFilter *tf = vtkTransformPolyDataFilter::New();
tf->SetTransform( t );
tf->SetInput( testPolyD );
tf->Update();

vtkOrientedGlyphContourRepresentation* contourRep = 
vtkOrientedGlyphContourRepresentation::New();
vtkContourWidget* contourWidget = vtkContourWidget::New();
contourWidget->SetInteractor(this->m_ImageView->GetImageViewer(0)->GetInteractor());
contourWidget->SetRepresentation(contourRep);
contourWidget->On();

contourWidget->Initialize(iView);

vtkPolyData* contour = contourRep->GetContourRepresentationAsPolyData();

/***************************************************************************/

then, if I plot this polydata, I get something like in the enclosed png 
in blue.
I roughly added in green the nodes I get while using the vtkContourWidget.
The nodes are in the good position but the data hasn't the good "shape".
I also roughly draw in red the polydata I would like to have in my 
vtkContourWidget.
The expected shape would be the same as the one I get just after 
applying the marching squares but I can't use directly the output of the 
marching square filter since it contains no point and no usable line.

I must be missing something but what...

Thanks,

Nicolas






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