extract one slice of a volume

[Adrian Anner]

hello

I want to execute the Trehsold filter (and display the result) on one slice
of a volume.
I tried the following :

vtkExtractVOI *extractor = vtkExtractVOI::New();
   extractor->SetInput( v16Reader->GetOutput() );
   extractor->SetVOI( 0, x-1, 0, y-1, slice, slice );
   extractor->Update();

vtkImageThreshold *threshold = vtkImageThreshold::New();
   threshold->ThresholdByUpper( maxThresh );
   threshold->SetInValue(0);
   threshold->SetOutValue(255);
   threshold->SetInput( extractor->GetOutput() );
   threshold->Update();

but it crashs at the statement  threshold->Update() : couldn't read at
adress xxxxxx

if I change the order :

vtkImageThreshold *threshold = vtkImageThreshold::New();
   threshold->ThresholdByUpper( maxThresh );
   threshold->SetInValue(0);
   threshold->SetOutValue(255);
   threshold->SetInput( v16Reader->GetOutput() );
   threshold->Update();

vtkExtractVOI *extractor = vtkExtractVOI::New();
   extractor->SetInput( threshold->GetOutput() );
   extractor->SetVOI( 0, x-1, 0, y-1, slice, slice );
   extractor->Update();

it works fine, but I have to execute the threshold filter over all slices.

any idea ?

thanks

Adrian



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