[Insight-users] Runtime error while performing update.

[Luis Ibanez]

Hi Ruby,


1) It is likely that your application is throwing an
    Exception. Please put a try/catch block around the
    code that triggers the execution or your ITK-VTK
    pipeline, and print out the description message
    returned by the eventual exception.


2) About your choice of pixel type:

    You should consider :

      A- What is the actual dynamic range of the input image
      B- What are you going to do with the GradientMagnitude image
      C- How strong are the gradients in your image.

    In typical medical images, gradient magnitudes are not too
    large, because they usually lack strong discontinuities.
    An easy experiment for you is to declare first your image
    as "float", run it through the GradientMagnitude filter
    declared as ImageFloat to ImageFloat, and then use the
    MaximumMinimum image calculator in order to find the
    max and min values of the gradient magnitude.  It is quite
    likely that the minimum will be zero.  If you find that the
    maximum is a small integer number (e.g. 35 or 55...), then
    you may want to use floats for computing the gradient magnitude
    in your actual application, or at least introduce some rescaling
    filter like the RescaleIntensityImageFilter.

    If the maximum gradient magnitude turns out to be a large integer
    then you will have to analyze what sort of operations are you
    doing with those integers afterward, since  you may risk to
    saturate the integer range with the subsequent operations.



The choice of pixel type is critical in a medical application
and deserves to be carefully analyzed.


Regards,


    Luis




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

Ruby Shamir wrote:
> Hi all,
> 
> I tried to convert vtkImageData to itk::image (using
> VTKImageToImageFilter)
> 
> , filter it with GradientMagnitudeImageFilter and then 
> 
> to convert it back to vtkImageData (using ImageToVTKImageFilter).
> 
> When tried to call update() the program terminates and display a
> message:
> 
> "This application has requested the Runtime to terminate it in an
> unusual way.
>  Please contact the application's support team for more information"  
> 
> (See code below)
> 
> My questions are:
> 
> 1. Why does it happen and how to avoid it?
> 
> 2. How can I now what image type to define?
>    (the data is 3D, but how can I know which pixel type to choose (I
> choose unsigned int because for no reason))
> 
> 
> 
> vtkImageData * showVolume::cleanImageData (vtkImageData *
> originalImageData){
> 	
> 	typedef itk::Image<unsigned int, 3>    ImageType;
> 
> 	typedef itk::ImageToVTKImageFilter<ImageType>
> itkToVtkConnectorType;
> 	typedef itk::VTKImageToImageFilter<ImageType>
> vtkToItkConnectorType;
> 	
> 	typedef itk::GradientMagnitudeImageFilter<ImageType,ImageType>
> gradientFilterType;
> 	typedef itk::DiscreteGaussianImageFilter<ImageType, ImageType>
> gaussianFilterType;
> 
> 	itkToVtkConnectorType::Pointer itkToVtkConnector =
> itkToVtkConnectorType::New();
> 	vtkToItkConnectorType::Pointer vtkToItkConnector =
> vtkToItkConnectorType::New();
> 	gradientFilterType::Pointer    gradientFilter    =
> gradientFilterType::New();
>     
> 	vtkToItkConnector->SetInput(originalImageData);
>     
> 	gradientFilter ->SetInput(vtkToItkConnector->GetOutput());
>       gradientFilter ->Update();
> 
>       itkToVtkConnector->SetInput(gradientFilter->GetOutput());
>  
> 	return (itkToVtkConnector->GetOutput());
> 
> }
> 
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk.org
> http://www.itk.org/mailman/listinfo/insight-users
>