VTK/Examples/Cxx/ImageData/IterateImageData

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

It is EXTREMELY important to ensure you set the ImageData to the correct data type to ensure it stores your data correctly as well as works with filters further down the pipeline. You can set the data type with something like: 

 imageData->SetScalarTypeToUnsignedShort();

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})
 
if (APPLE)
  add_executable(IterateImageData MACOSX_BUNDLE IterateImageData.cxx)
else()
  add_executable(IterateImageData IterateImageData.cxx)
endif()
 
if(VTK_LIBRARIES)
  target_link_libraries(IterateImageData ${VTK_LIBRARIES})
else()
  target_link_libraries(IterateImageData vtkHybrid )
endif()
Retrieved from "http://batchmake.org/Wiki/VTK/Examples/Cxx/ImageData/IterateImageData"
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