VTK/Examples/Cxx/ImageData/IterateImageData

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

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;
}

Please try the new VTKExamples website.

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)

if(VTK_LIBRARIES)
  target_link_libraries(IterateImageData ${VTK_LIBRARIES})
else()
  target_link_libraries(IterateImageData vtkHybrid vtkWidgets)
endif()

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.