ITK/Examples/Iterators/ShapedNeighborhoodIteratorManual

Crashes when initializing the iterator loop?

ShapedNeighborhoodIterator.cxx

<source lang="cpp">

1. include "itkImage.h"
2. include "itkShapedNeighborhoodIterator.h"
3. include "itkImageRegionIterator.h"

1. include <itkImageToVTKImageFilter.h>

1. include "vtkImageViewer.h"
2. include "vtkRenderWindowInteractor.h"
3. include "vtkSmartPointer.h"
4. include "vtkImageActor.h"
5. include "vtkInteractorStyleImage.h"
6. include "vtkRenderer.h"

typedef itk::Image<unsigned char, 2> ImageType;

void CreateImage(ImageType::Pointer image);

int main(int, char*[]) {

 ImageType::Pointer image = ImageType::New();
 ImageType::SizeType radius;
 radius[0] = 1;
 radius[1] = 1;

 typedef itk::ShapedNeighborhoodIterator<ImageType> IteratorType;
 IteratorType iterator(radius, image, image->GetLargestPossibleRegion());

 /*
 // a smaller region
 ImageType::RegionType region;
 ImageType::IndexType start;
 start[0] = 5;
 start[1] = 5;

 ImageType::SizeType size;
 size[0] = 3;
 size[1] = 4;

 region.SetSize(size);
 region.SetIndex(start);
 IteratorType iterator(radius, image, region);
 */

 //This is a weird way to activate offsets//
 /*
 IteratorType::OffsetType top = Template:0,-1;
 IteratorType::OffsetType bottom = Template:0,1;
 IteratorType::OffsetType left = Template:-1,0;
 IteratorType::OffsetType right = Template:1,0;
 iterator.ActivateOffset(top);
 iterator.ActivateOffset(bottom);
 iterator.ActivateOffset(left);
 iterator.ActivateOffset(right);
 */

 //This way seems more appropriate//
 for (float y = -radius; y <= radius; y++)
     {
     for (float x = -radius; x <= radius; x++)
       {
       IteratorType::OffsetType off;
       
       float dis = vcl_sqrt( x*x + y*y );
       if (dis <= radius)
         {
         off[0] = static_cast<int>(x);
         off[1] = static_cast<int>(y);
         iterator.ActivateOffset(off);
         }
       }
     }

 for(iterator.GoToBegin(); !iterator.IsAtEnd(); ++iterator) // Crashes here!
 //The for loop syntax is correct, the crash is caused by referencing the out of bound pixels// 
 //which should have been handled with boundary checking, the best way to handle boundary pixels in ITK is to use FaceList//
   {
   //The offset "top" is out of bound in the first iteration and when you iterate over the first row of the image//
   std::cout << "top: " << iterator[top] << std::endl;
   //The offset "bottom" is out of bound when you iterate over the last row of the image//
   std::cout << "bottom: " << iterator[bottom] << std::endl;
   //The offset "left" is out of bound in the first iteration and when you iterate over the first column of the image//
   std::cout << "left: " << iterator[left] << std::endl;
   //The offset "bottom" is out of bound when you iterate over the last column of the image//
   std::cout << "right: " << iterator[right] << std::endl;
   }

 // Visualize
 typedef itk::ImageToVTKImageFilter<ImageType> ConnectorType;
 ConnectorType::Pointer connector = ConnectorType::New();
 connector->SetInput(image);

 vtkSmartPointer<vtkImageActor> actor =
   vtkSmartPointer<vtkImageActor>::New();
 actor->SetInput(connector->GetOutput());

 vtkSmartPointer<vtkRenderWindow> renderWindow =
   vtkSmartPointer<vtkRenderWindow>::New();

 vtkSmartPointer<vtkRenderWindowInteractor> interactor =
   vtkSmartPointer<vtkRenderWindowInteractor>::New();
 interactor->SetRenderWindow(renderWindow);

 vtkSmartPointer<vtkRenderer> renderer =
   vtkSmartPointer<vtkRenderer>::New();
 renderWindow->AddRenderer(renderer);

 renderer->AddActor(actor);
 renderer->ResetCamera();

 renderWindow->Render();

 vtkSmartPointer<vtkInteractorStyleImage> style =
   vtkSmartPointer<vtkInteractorStyleImage>::New();

 interactor->SetInteractorStyle(style);

 interactor->Start();

 return EXIT_SUCCESS;

}

void CreateImage(ImageType::Pointer image) {

 // Create an image
 ImageType::RegionType region;
 ImageType::IndexType start;
 start[0] = 0;
 start[1] = 0;

 ImageType::SizeType size;
 size[0] = 20;
 size[1] = 30;

 region.SetSize(size);
 region.SetIndex(start);

 image->SetRegions(region);
 image->Allocate();

 itk::ImageRegionIterator<ImageType> imageIterator(image,region);

 while(!imageIterator.IsAtEnd())
   {
   imageIterator.Set(0);

   ++imageIterator;
   }

} </source>

CMakeLists.txt

<source lang="cmake"> cmake_minimum_required(VERSION 2.6)

PROJECT(ShapedNeighborhoodIterator)

include_directories(/home/doriad/src/ITK/Wrapping/WrapITK/ExternalProjects/ItkVtkGlue/src/)

FIND_PACKAGE(VTK REQUIRED) INCLUDE(${VTK_USE_FILE})

FIND_PACKAGE(ITK REQUIRED) INCLUDE(${ITK_USE_FILE})

ADD_EXECUTABLE(ShapedNeighborhoodIterator ShapedNeighborhoodIterator.cxx) TARGET_LINK_LIBRARIES(ShapedNeighborhoodIterator vtkHybrid ITKNumerics ITKBasicFilters ITKCommon ITKIO)

</source>