# MaskPointsFilter

VTKExamples/Cxx/Points/MaskPointsFilter

### Description

Warning

The classes used in this example require vtk 7.1 or later.

### Code

MaskPointsFilter.cxx

    #include <vtkSmartPointer.h>
    #include <vtkMaskPointsFilter.h>

    #include <vtkBoundedPointSource.h>
    #include <vtkImageData.h>
    #include <vtkCone.h>
    #include <vtkSampleImplicitFunctionFilter.h>
    #include <vtkImageThreshold.h>
    #include <vtkBoundedPointSource.h>

    #include <vtkMetaImageReader.h>

    #include <vtkSphereSource.h>
    #include <vtkGlyph3D.h>

    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkCamera.h>

    static vtkSmartPointer<vtkImageData> CreatePoints();

    int main (int argc, char *argv[])
    {
      vtkSmartPointer<vtkImageData> imageMask;
      if (argc < 2)
      {
        imageMask = CreatePoints();
      }
      else
      {
        int upper = 1100;
        if (argc > 2)
        {
          upper = atoi(argv[2]);
        }
        // Read the volume data
        vtkSmartPointer<vtkMetaImageReader> reader =
          vtkSmartPointer<vtkMetaImageReader>::New();
        reader->SetFileName (argv[1]);
        reader->Update();

        vtkSmartPointer<vtkImageThreshold> threshold =
          vtkSmartPointer<vtkImageThreshold>::New();
        threshold->SetInputConnection(reader->GetOutputPort());
        threshold->ThresholdByUpper(upper);
        threshold->SetOutputScalarTypeToUnsignedChar();
        threshold->ReplaceInOn();
        threshold->SetInValue(255);
        threshold->SetOutValue(0);
        threshold->ReplaceOutOn();
        threshold->Update();
        imageMask = vtkImageData::SafeDownCast(threshold->GetOutput());
      }
      vtkSmartPointer<vtkBoundedPointSource> pointSource =
        vtkSmartPointer<vtkBoundedPointSource>::New();
      pointSource->SetNumberOfPoints(100000);
      pointSource->SetBounds(imageMask->GetBounds());

      vtkSmartPointer<vtkMaskPointsFilter> maskPoints =
        vtkSmartPointer<vtkMaskPointsFilter>::New();
      maskPoints->SetInputConnection(pointSource->GetOutputPort());
      maskPoints->SetMaskData(imageMask);

      double radius = imageMask->GetSpacing()[0] * 4.0;
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetRadius(radius);

      vtkSmartPointer<vtkGlyph3D> glyph =
        vtkSmartPointer<vtkGlyph3D>::New();
      glyph->SetInputConnection(maskPoints->GetOutputPort());
      glyph->SetSourceConnection(sphereSource->GetOutputPort());
      glyph->ScalingOff();
      glyph->Update();

      vtkSmartPointer<vtkPolyDataMapper> glyphMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      glyphMapper->SetInputConnection(glyph->GetOutputPort());
      glyphMapper->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> glyphActor =
        vtkSmartPointer<vtkActor>::New();
      glyphActor->SetMapper(glyphMapper);
      glyphActor->GetProperty()->SetColor(0.8900, 0.8100, 0.3400);

      // Create graphics stuff
      //
      vtkSmartPointer<vtkRenderer> ren1 =
        vtkSmartPointer<vtkRenderer>::New();
      ren1->SetBackground(.3, .4, .6);

      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->AddRenderer(ren1);
      renWin->SetSize(512,512);

      vtkSmartPointer<vtkRenderWindowInteractor> iren =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      iren->SetRenderWindow(renWin);

      // Add the actors to the renderer, set the background and size
      //
      ren1->AddActor(glyphActor);

      // Generate an interesting view
      //
      ren1->GetActiveCamera()->SetPosition (1, 0, 0);
      ren1->GetActiveCamera()->SetFocalPoint (0, 1, 0);
      ren1->GetActiveCamera()->SetViewUp (0, 0, -1);
      ren1->GetActiveCamera()->Azimuth(30);
      ren1->GetActiveCamera()->Elevation(30);
      ren1->ResetCamera();
      ren1->GetActiveCamera()->Dolly(1.0);
      ren1->ResetCameraClippingRange();

      iren->Initialize();
      iren->Start();

      return EXIT_SUCCESS;
    }

    static vtkSmartPointer<vtkImageData> CreatePoints()
    {
      vtkSmartPointer<vtkImageData> imageMask =
        vtkSmartPointer<vtkImageData>::New();

      vtkSmartPointer<vtkImageData> image =
        vtkSmartPointer<vtkImageData>::New();
      image->SetDimensions(256,256,256);
      image->AllocateScalars(VTK_DOUBLE,1);
      image->SetSpacing(5.0/255.0, 5.0/255.0, 5.0/255.0);
      image->SetOrigin(-2.5, -2.5, -2.5);
      vtkSmartPointer<vtkCone> implicitFunction =
        vtkSmartPointer<vtkCone>::New();
      vtkSmartPointer<vtkSampleImplicitFunctionFilter> sample =
        vtkSmartPointer<vtkSampleImplicitFunctionFilter>::New();
      sample->SetImplicitFunction(implicitFunction);
      sample->SetInputData(image);

      vtkSmartPointer<vtkImageThreshold> threshold =
        vtkSmartPointer<vtkImageThreshold>::New();
      threshold->SetInputConnection(sample->GetOutputPort());
      threshold->ThresholdByLower(.5);
      threshold->SetOutputScalarTypeToUnsignedChar();
      threshold->ReplaceInOn();
      threshold->SetInValue(255);
      threshold->SetOutValue(0);
      threshold->ReplaceOutOn();
      threshold->Update();
      imageMask = vtkImageData::SafeDownCast(threshold->GetOutput());
      return imageMask;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(MaskPointsFilter)

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

    add_executable(MaskPointsFilter MACOSX_BUNDLE MaskPointsFilter.cxx )

    target_link_libraries(MaskPointsFilter ${VTK_LIBRARIES})

### Download and Build MaskPointsFilter

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

    cd MaskPointsFilter/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:

    ./MaskPointsFilter

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.