VTK/Examples/Cxx/PolyData/PolyDataToImageData

• Contributed by: Lars Friedrich

Brief Description

This example generates a sphere (prerequisite: closed surface of type vtkPolyData) and converts it into volume representation (vtkImageData) where the foreground voxels are 255 (inside) and the background voxels are 0 (outside). Internally vtkPolyDataToImageStencil is utilized. The resultant image is saved to disk in metaimage file format (SphereVolume.mhd).

PolyDataToImageData.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkImageData.h>
#include <vtkSphereSource.h>
#include <vtkMetaImageWriter.h>
#include <vtkPolyDataToImageStencil.h>
#include <vtkImageStencil.h>
#include <vtkPointData.h>

/**
 * This program generates a sphere (closed surface, vtkPolyData) and converts it into volume
 * representation (vtkImageData) where the foreground voxels are 1 and the background voxels are
 * 0. Internally vtkPolyDataToImageStencil is utilized. The resultant image is saved to disk 
 * in metaimage file format (SphereVolume.mhd).
 */
int main(int, char *[])
{  
  vtkSmartPointer<vtkSphereSource> sphereSource = 
    vtkSmartPointer<vtkSphereSource>::New();  
  sphereSource->SetRadius(20);
  sphereSource->SetPhiResolution(30);
  sphereSource->SetThetaResolution(30);
  vtkSmartPointer<vtkPolyData> pd = sphereSource->GetOutput();
  sphereSource->Update();

  vtkSmartPointer<vtkImageData> whiteImage = 
    vtkSmartPointer<vtkImageData>::New();    
  double bounds[6];
  pd->GetBounds(bounds);
  double spacing[3]; // desired volume spacing
  spacing[0] = 0.5;
  spacing[1] = 0.5;
  spacing[2] = 0.5;
  whiteImage->SetSpacing(spacing);

  // compute dimensions
  int dim[3];
  for (int i = 0; i < 3; i++)
    {
    dim[i] = static_cast<int>(ceil((bounds[i * 2 + 1] - bounds[i * 2]) / spacing[i]));
    }
  whiteImage->SetDimensions(dim);
  whiteImage->SetExtent(0, dim[0] - 1, 0, dim[1] - 1, 0, dim[2] - 1);

  double origin[3];
  origin[0] = bounds[0] + spacing[0] / 2;
  origin[1] = bounds[2] + spacing[1] / 2;
  origin[2] = bounds[4] + spacing[2] / 2;
  whiteImage->SetOrigin(origin);

#if VTK_MAJOR_VERSION <= 5
  whiteImage->SetScalarTypeToUnsignedChar();
  whiteImage->AllocateScalars();
#else
  whiteImage->AllocateScalars(VTK_UNSIGNED_CHAR,1);
#endif
  // fill the image with foreground voxels:
  unsigned char inval = 255;
  unsigned char outval = 0;
  vtkIdType count = whiteImage->GetNumberOfPoints();
  for (vtkIdType i = 0; i < count; ++i)
    {
    whiteImage->GetPointData()->GetScalars()->SetTuple1(i, inval);
    }

  // polygonal data --> image stencil:
  vtkSmartPointer<vtkPolyDataToImageStencil> pol2stenc = 
    vtkSmartPointer<vtkPolyDataToImageStencil>::New();
#if VTK_MAJOR_VERSION <= 5
  pol2stenc->SetInput(pd);
#else
  pol2stenc->SetInputData(pd);
#endif
  pol2stenc->SetOutputOrigin(origin);
  pol2stenc->SetOutputSpacing(spacing);
  pol2stenc->SetOutputWholeExtent(whiteImage->GetExtent());
  pol2stenc->Update();

  // cut the corresponding white image and set the background:
  vtkSmartPointer<vtkImageStencil> imgstenc = 
    vtkSmartPointer<vtkImageStencil>::New();
#if VTK_MAJOR_VERSION <= 5
  imgstenc->SetInput(whiteImage);
  imgstenc->SetStencil(pol2stenc->GetOutput());
#else
  imgstenc->SetInputData(whiteImage);
  imgstenc->SetStencilConnection(pol2stenc->GetOutputPort());
#endif
  imgstenc->ReverseStencilOff();
  imgstenc->SetBackgroundValue(outval);
  imgstenc->Update();

  vtkSmartPointer<vtkMetaImageWriter> writer = 
    vtkSmartPointer<vtkMetaImageWriter>::New();
  writer->SetFileName("SphereVolume.mhd");
#if VTK_MAJOR_VERSION <= 5
  writer->SetInput(imgstenc->GetOutput());
#else
  writer->SetInputData(imgstenc->GetOutput());
#endif
  writer->Write();  
  
  return EXIT_SUCCESS;
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(PolyDataToImageData)

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

add_executable(PolyDataToImageData MACOSX_BUNDLE PolyDataToImageData.cxx)

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

Download and Build PolyDataToImageData

Click here to download PolyDataToImageData. and its CMakeLists.txt file.

Once the tarball PolyDataToImageData.tar has been downloaded and extracted,

cd PolyDataToImageData/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:

./PolyDataToImageData

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.

After adding visualization, replace current screenshot with div tag for baseline image.