[Insight-users] trouble using itkApproximateSignedDistanceMapImageFilter

[Alexandra Lauric]

Hi,
I have some trouble using itkApproximateSignedDistanceMapImageFilter on
several DICOM datasets, all of size 256x256x229. Basically, I'm thresholding
the data to a binary image, using a cast filter from short to double (I've
tried float, too) and applying the distance field filter. For some data sets
this works fine. On others I get the following error:

*excp    {m_Location="void __thiscall
itk::MultiThreader::SingleMethodExecute(void)" m_Description="itk::ERROR:
MultiThreader(02144028): Exception occurred during SingleMethodExecute
c:\itk\insight\code\algorithms\itkIsoContourDistanceImageFilter.txx:330:
itk::ERROR: IsoContourDistanceImageFilter(054C0948): Gradient norm is lower
than pixel precision" m_What="..\..\..\Insight\Code\Common\itkMultiThreade
.  *

All datasets have the same characteristics. Sometimes, if it doesn't work on
the whole dataset, it will work on some subsets, but I couldn't find a
pattern. My code is attached below. Any help would be greatly appreciated.

Thank  you,
Alex

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  typedef signed short    PixelType;
  const unsigned int      Dimension = 3;

  typedef itk::Image< PixelType, Dimension >         ImageType;
  typedef itk::ImageSeriesReader< ImageType >     ReaderType;


  typedef itk::GDCMImageIO                             ImageIOType;
  typedef itk::GDCMSeriesFileNames                NamesGeneratorType;

  ImageIOType::Pointer gdcmIO = ImageIOType::New();
  NamesGeneratorType::Pointer namesGenerator = NamesGeneratorType::New();

  namesGenerator->SetInputDirectory( argv[1] );

  const ReaderType::FileNamesContainer & filenames =
                            namesGenerator->GetInputFileNames();

  ReaderType::Pointer reader = ReaderType::New();

  reader->SetImageIO( gdcmIO );
  reader->SetFileNames( filenames );


  try
    {
    reader->Update();
    }
  catch (itk::ExceptionObject &excp)
    {
    std::cerr << "Exception thrown while writing the image" << std::endl;
    std::cerr << excp << std::endl;
    return EXIT_FAILURE;
    }


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


    typedef double    InternPixelType;

    typedef  itk::Image< InternPixelType, 3 >         InternImageType;
    typedef  itk::ConnectedThresholdImageFilter< ImageType,  ImageType >
ThreshFilterType;
    typedef  itk::MinimumMaximumImageCalculator< ImageType>
MinMaxFilterType;
    typedef  itk::CastImageFilter< ImageType, InternImageType >
CastFilterType;
    typedef  itk::ApproximateSignedDistanceMapImageFilter< InternImageType,
InternImageType >   DistanceFilterType;

    MinMaxFilterType::Pointer minMaxFilter = MinMaxFilterType::New();
    ThreshFilterType::Pointer threshFilter = ThreshFilterType::New();
    DistanceFilterType::Pointer distFilter = DistanceFilterType::New();
    CastFilterType::Pointer castFilter = CastFilterType::New();

    PixelType maxValue;
    PixelType minValue;

    if(argc == 4)
        minValue = atoi(argv[3]);
    else
        minValue = 600;

    itk::Index<3> seed;

    minMaxFilter->SetImage(reader->GetOutput());
    minMaxFilter->Compute();
    maxValue = minMaxFilter->GetMaximum();
    seed = minMaxFilter->GetIndexOfMaximum();

    threshFilter->SetInput(reader->GetOutput());
    threshFilter->SetUpper( maxValue );
    threshFilter->SetLower( minValue );
    threshFilter->SetReplaceValue(255);
    threshFilter->AddSeed( seed );
    threshFilter->Update();

    castFilter->SetInput(threshFilter->GetOutput());
    castFilter->Update();

    distFilter->SetInput(castFilter->GetOutput());
    distFilter->SetInsideValue(255);
    distFilter->SetOutsideValue(0);
    distFilter->Update();

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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