# IterateImageData

VTKExamples/Cxx/ImageData/IterateImageData

### Description

This example demonstrates how to set and access locations in a 3D image.

### Code

IterateImageData.cxx

    #include <vtkVersion.h>
    #include <vtkSmartPointer.h>
    #include <vtkImageData.h>

    int main(int, char *[])
    {
      // Create an image data
      vtkSmartPointer<vtkImageData> imageData =
        vtkSmartPointer<vtkImageData>::New();

      // Specify the size of the image data
      imageData->SetDimensions(2,3,1);
    #if VTK_MAJOR_VERSION <= 5
      imageData->SetNumberOfScalarComponents(1);
      imageData->SetScalarTypeToDouble();
    #else
      imageData->AllocateScalars(VTK_DOUBLE,1);
    #endif

      int* dims = imageData->GetDimensions();
      // int dims[3]; // can't do this

      std::cout << "Dims: " << " x: " << dims[0] << " y: " << dims[1] << " z: " << dims[2] << std::endl;

      std::cout << "Number of points: " << imageData->GetNumberOfPoints() << std::endl;
      std::cout << "Number of cells: " << imageData->GetNumberOfCells() << std::endl;

      // Fill every entry of the image data with "2.0"
      for (int z = 0; z < dims[2]; z++)
      {
        for (int y = 0; y < dims[1]; y++)
        {
          for (int x = 0; x < dims[0]; x++)
          {
            double* pixel = static_cast<double*>(imageData->GetScalarPointer(x,y,z));
            pixel[0] = 2.0;
          }
        }
      }

      // Retrieve the entries from the image data and print them to the screen
      for (int z = 0; z < dims[2]; z++)
      {
        for (int y = 0; y < dims[1]; y++)
        {
          for (int x = 0; x < dims[0]; x++)
          {
            double* pixel = static_cast<double*>(imageData->GetScalarPointer(x,y,z));
            // do something with v
            std::cout << pixel[0] << " ";
          }
          std::cout << std::endl;
        }
        std::cout << std::endl;
      }

      // Access the data linearly
      /*
        vtkSmartPointer<vtkImageData> image =
        vtkSmartPointer<vtkImageData>::New();
      image->SetExtent(0,1,0,1,0,0);
      image->SetScalarTypeToInt();
      image->SetNumberOfScalarComponents(1);

      int* pixel;

      pixel = static_cast<int*>(image->GetScalarPointer(0,0,0));
      pixel[0] = 1;

      pixel = static_cast<int*>(image->GetScalarPointer(1,0,0));
      pixel[0] = 2;

      pixel = static_cast<int*>(image->GetScalarPointer(0,1,0));
      pixel[0] = 3;

      pixel = static_cast<int*>(image->GetScalarPointer(1,1,0));
      pixel[0] = 4;

      vtkIntArray* scalars = vtkIntArray::SafeDownCast(image->GetPointData()->GetArray("ImageScalars"));
      std::cout << "Scalars has " << scalars->GetNumberOfComponents() << " components" << std::endl;
      std::cout << "Scalars has " << scalars->GetNumberOfTuples() << " tuples" << std::endl;

      for(vtkIdType i = 0; i < scalars->GetNumberOfTuples(); i++)
        {
        std::cout << scalars->GetValue(i) << std::endl;
        }
      */
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(IterateImageData)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(IterateImageData MACOSX_BUNDLE IterateImageData.cxx)

    target_link_libraries(IterateImageData ${VTK_LIBRARIES})

### Download and Build IterateImageData

Click here to download IterateImageData and its CMakeLists.txt file. Once the tarball IterateImageData.tar has been downloaded and extracted,

    cd IterateImageData/build

If VTK is installed:

    cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

    cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

    make

and run it:

    ./IterateImageData

WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.