# MassProperties

VTKExamples/Cxx/Utilities/MassProperties

### Description

This example uses vtkMassProperties to compute the volume of a closed mesh. vtkMassProperties requires triangles with consistent ordering. This example uses vtkFillHolesFilter and vtkTriangleFilter to ensure a closed, triangulated mesh. vtkPolyDataNormals enforces consistent normals.

If run with no arguments, a vtkSphereSource generates the vtkPolyData. Of given a file containing vtkPolyData, it computes that data's volume and surface area.

Cite

(Alyassin A.M. et al, "Evaluation of new algorithms for the interactive measurement of surface area and volume", Med Phys 21(6) 1994.)

### Code

MassProperties.cxx

    #include <vtkSmartPointer.h>
    #include <vtkMassProperties.h>
    #include <vtkTriangleFilter.h>
    #include <vtkFillHolesFilter.h>
    #include <vtkPolyDataNormals.h>

    #include <vtkBYUReader.h>
    #include <vtkOBJReader.h>
    #include <vtkPLYReader.h>
    #include <vtkPolyDataReader.h>
    #include <vtkSTLReader.h>
    #include <vtkXMLPolyDataReader.h>
    #include <vtkSphereSource.h>
    #include <vtksys/SystemTools.hxx>

    namespace
    {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char *fileName);
    }

    int main (int argc, char *argv[])
    {
      vtkSmartPointer<vtkPolyData> polyData = ReadPolyData(argc > 1 ? argv[1] : "");;

      vtkSmartPointer<vtkFillHolesFilter> fillHolesFilter =
        vtkSmartPointer<vtkFillHolesFilter>::New();
      fillHolesFilter->SetInputData(polyData);
      fillHolesFilter->SetHoleSize(1000.0);

      vtkSmartPointer<vtkTriangleFilter> triangleFilter =
        vtkSmartPointer<vtkTriangleFilter>::New();
      triangleFilter->SetInputConnection(fillHolesFilter->GetOutputPort());

      // Make the triangle windong order consistent
      vtkSmartPointer<vtkPolyDataNormals> normals =
        vtkSmartPointer<vtkPolyDataNormals>::New();
      normals->SetInputConnection(triangleFilter->GetOutputPort());
      normals->ConsistencyOn();
      normals->SplittingOff();

      vtkSmartPointer<vtkMassProperties> massProperties =
        vtkSmartPointer<vtkMassProperties>::New();
      massProperties->SetInputConnection(normals->GetOutputPort());
      massProperties->Update();
      std::cout << "Volume: " << massProperties->GetVolume() << std::endl
                << "    VolumeX: " << massProperties->GetVolumeX() << std::endl
                << "    VolumeY: " << massProperties->GetVolumeY() << std::endl
                << "    VolumeZ: " << massProperties->GetVolumeZ() << std::endl
                << "Area:   " << massProperties->GetSurfaceArea() << std::endl
                << "    MinCellArea: " << massProperties->GetMinCellArea() << std::endl
                << "    MinCellArea: " << massProperties->GetMaxCellArea() << std::endl
                << "NormalizedShapeIndex: " << massProperties->GetNormalizedShapeIndex() << std::endl;

      return EXIT_SUCCESS;
    }

    namespace
    {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char *fileName)
    {
      vtkSmartPointer<vtkPolyData> polyData;
      std::string extension = vtksys::SystemTools::GetFilenameExtension(std::string(fileName));
      if (extension == ".ply")
      {
        vtkSmartPointer<vtkPLYReader> reader =
          vtkSmartPointer<vtkPLYReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtp")
      {
        vtkSmartPointer<vtkXMLPolyDataReader> reader =
          vtkSmartPointer<vtkXMLPolyDataReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".obj")
      {
        vtkSmartPointer<vtkOBJReader> reader =
          vtkSmartPointer<vtkOBJReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".stl")
      {
        vtkSmartPointer<vtkSTLReader> reader =
          vtkSmartPointer<vtkSTLReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtk")
      {
        vtkSmartPointer<vtkPolyDataReader> reader =
          vtkSmartPointer<vtkPolyDataReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".g")
      {
        vtkSmartPointer<vtkBYUReader> reader =
          vtkSmartPointer<vtkBYUReader>::New();
        reader->SetGeometryFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else
      {
        vtkSmartPointer<vtkSphereSource> source =
          vtkSmartPointer<vtkSphereSource>::New();
        source->SetPhiResolution(51);
        source->SetThetaResolution(51);
        source->Update();
        polyData = source->GetOutput();
      }
      return polyData;
    }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(MassProperties)

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

    add_executable(MassProperties MACOSX_BUNDLE MassProperties.cxx )

    target_link_libraries(MassProperties ${VTK_LIBRARIES})

### Download and Build MassProperties

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

    cd MassProperties/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:

    ./MassProperties

WINDOWS USERS

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