[Insight-users] runtime error in itk::ConstNeighborhoodIterator

[Miller, James V (Research)]

Aaron, 
 
The ExtractImageFilter needs to be Update()'d  before you can walk its output with an interator.  
 
Jim

	-----Original Message----- 
	From: insight-users-bounces at itk.org on behalf of Aaron Skewes 
	Sent: Wed 3/30/2005 2:48 PM 
	To: insight-users at itk.org 
	Cc: 
	Subject: [Insight-users] runtime error in itk::ConstNeighborhoodIterator
	
	

	Dear Sirs,

	 

	I am attempting to extract a slice normal to the z-axis from a 3d image, and create a ConstNeighborhoodIterator with a scaleable radius to perform some calculations. When the code executes the conditions in the for loop (boundaries of the neighborhood) I receive a runtime error. Any ideas why this may occur?

	 

	 

	            typedef    float    FilterPixelType;

	            typedef    float    ItPixelType;

	            // Define the image type, dimensions

	            typedef itk::Image< FilterPixelType,  DIMENSION >   FilterImageType;

	            typedef itk::Image< ItPixelType, 2 > ItImageType;

	 

	            typedef itk::ImageFileReader< FilterImageType >   ReaderType;   

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

	            reader->SetFileName( inputFileName  );

	 

	            reader->SetFileName(inputFileName );

	  

	            try

	            {

	                        reader->Update();

	            }

	            catch( itk::ExceptionObject & excp )

	            {

	                        std::cerr << "Problem reading the input file" << std::endl;

	                        std::cerr << excp << std::endl;

	                        return -1;

	            }

	 

	            //!Extract a slice from the image                

	            typedef itk::ExtractImageFilter< FilterImageType, ItImageType > ExtractFilterType;

	            ExtractFilterType::Pointer extractfilter = ExtractFilterType::New();  

	  

	            FilterImageType::RegionType inputRegion = reader->GetOutput()->GetLargestPossibleRegion();

	            FilterImageType::SizeType size = inputRegion.GetSize();

	            size[2] = 0;

	 

	            FilterImageType::IndexType start = inputRegion.GetIndex();

	            start[2] = 0;

	  

	            FilterImageType::RegionType desiredRegion;

	            desiredRegion.SetIndex( start );

	            desiredRegion.SetSize(  size  );

	 

	            extractfilter->SetExtractionRegion( desiredRegion );

	            extractfilter->SetInput( reader->GetOutput() );

	 

	            //set-up an iterator to preform convolution

	            typedef itk::ConstNeighborhoodIterator< ItImageType > NeighborhoodIteratorType;

	            NeighborhoodIteratorType::RadiusType radius;

	 

	            for (float sigma=sigmaMin; sigma<sigmaMax; sigma+=step_size) 

	            {                       

	                        //set scalable filter  width

	                        radius.Fill(sigma);

	                        NeighborhoodIteratorType it( radius, extractfilter->GetOutput(), extractfilter->GetOutput()->GetRequestedRegion());               

	                        

	                        for (it.GoToBegin(); !it.IsAtEnd(); ++it) !!!!!!!!!!!!!!!! RUNTINE ERROR HERE

	                        {

	                                    DO SOMETHING 

	           

	                        }                                   

	            }

	 

	Thanks,

	Aaron