# CarotidFlowGlyphs

VTKExamples/Cxx/VisualizationAlgorithms/CarotidFlowGlyphs

### Description

Visualizing blood flow in human carotid arteries. Cone glyphs indicate flow direction and magnitude.

Info

See Figure 6-43 in Chapter 6 the VTK Textbook.

Other Languages

See (Python)

### Code

CarotidFlowGlyphs.cxx

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkConeSource.h>
    #include <vtkContourFilter.h>
    #include <vtkGlyph3D.h>
    #include <vtkLookupTable.h>
    #include <vtkMaskPoints.h>
    #include <vtkNamedColors.h>
    #include <vtkOutlineFilter.h>
    #include <vtkPointData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkStructuredPoints.h>
    #include <vtkStructuredPointsReader.h>
    #include <vtkThresholdPoints.h>

    int main (int argc, char *argv[])
    {
      if (argc < 2)
      {
        std::cout << "Usage: " << argv[0] << " carotid.vtk" << std::endl;
        return EXIT_FAILURE;
      }

      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      vtkSmartPointer<vtkRenderer> ren1 =
        vtkSmartPointer<vtkRenderer>::New();

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

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

    // create pipeline
    //
      vtkSmartPointer<vtkStructuredPointsReader> reader =
        vtkSmartPointer<vtkStructuredPointsReader>::New();
      reader->SetFileName(argv[1]);

      vtkSmartPointer<vtkThresholdPoints> threshold =
        vtkSmartPointer<vtkThresholdPoints>::New();
      threshold->SetInputConnection(reader->GetOutputPort());
      threshold->ThresholdByUpper(200);

      vtkSmartPointer<vtkMaskPoints> mask =
        vtkSmartPointer<vtkMaskPoints>::New();
      mask->SetInputConnection(threshold->GetOutputPort());
      mask->SetOnRatio(5);

      vtkSmartPointer<vtkConeSource> cone =
        vtkSmartPointer<vtkConeSource>::New();
      cone->SetResolution(11);
      cone->SetHeight(1);
      cone->SetRadius(0.25);

      vtkSmartPointer<vtkGlyph3D> cones =
        vtkSmartPointer<vtkGlyph3D>::New();
      cones->SetInputConnection(mask->GetOutputPort());
      cones->SetSourceConnection(cone->GetOutputPort());
      cones->SetScaleFactor(0.4);
      cones->SetScaleModeToScaleByVector();

      vtkSmartPointer<vtkLookupTable> lut =
        vtkSmartPointer<vtkLookupTable>::New();
      lut->SetHueRange(.667, 0.0);
      lut->Build();

      double range[2];
      cones->Update();
      range[0] = cones->GetOutput()->GetPointData()->GetScalars()->GetRange()[0];
      range[1] = cones->GetOutput()->GetPointData()->GetScalars()->GetRange()[1];
      std::cout << "range: " << range[0] << ", " << range[1] << std::endl;

      vtkSmartPointer<vtkPolyDataMapper> vectorMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      vectorMapper->SetInputConnection(cones->GetOutputPort());
      vectorMapper->SetScalarRange(range[0], range[1]);
      vectorMapper->SetLookupTable(lut);

      vtkSmartPointer<vtkActor> vectorActor =
        vtkSmartPointer<vtkActor>::New();
      vectorActor->SetMapper(vectorMapper);

    // contours of speed
      vtkSmartPointer<vtkContourFilter> iso =
        vtkSmartPointer<vtkContourFilter>::New();
      iso->SetInputConnection(reader->GetOutputPort());
      iso->SetValue(0, 175);

      vtkSmartPointer<vtkPolyDataMapper> isoMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      isoMapper->SetInputConnection(iso->GetOutputPort());
      isoMapper->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> isoActor =
        vtkSmartPointer<vtkActor>::New();
      isoActor->SetMapper(isoMapper);
      isoActor->GetProperty()->SetRepresentationToWireframe();
      isoActor->GetProperty()->SetOpacity(0.25);

    // outline
      vtkSmartPointer<vtkOutlineFilter> outline =
        vtkSmartPointer<vtkOutlineFilter>::New();
      outline->SetInputConnection(reader->GetOutputPort());

      vtkSmartPointer<vtkPolyDataMapper> outlineMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      outlineMapper->SetInputConnection(outline->GetOutputPort());

      vtkSmartPointer<vtkActor> outlineActor =
        vtkSmartPointer<vtkActor>::New();
      outlineActor->SetMapper(outlineMapper);
      outlineActor->GetProperty()->SetColor(colors->GetColor3d("Black").GetData());

    // Add the actors to the renderer, set the background and size
    //
      ren1->AddActor(outlineActor);
      ren1->AddActor(vectorActor);
      ren1->AddActor(isoActor);
      ren1->SetBackground(colors->GetColor3d("Wheat").GetData());
      renWin->SetSize(640, 480);

      vtkSmartPointer<vtkCamera> cam1 =
        vtkSmartPointer<vtkCamera>::New();
      cam1->SetClippingRange(17.4043, 870.216);
      cam1->SetFocalPoint(136.71, 104.025, 23);
      cam1->SetPosition(204.747, 258.939, 63.7925);
      cam1->SetViewUp(-0.102647, -0.210897, 0.972104);
      cam1->Zoom(1.6);
      ren1->SetActiveCamera(cam1);

    // render the image
    //
      renWin->Render();
      iren->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(CarotidFlowGlyphs)

    find_package(VTK COMPONENTS
      vtkCommonColor
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersCore
      vtkFiltersModeling
      vtkFiltersSources
      vtkIOLegacy
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping CarotidFlowGlyphs: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(CarotidFlowGlyphs MACOSX_BUNDLE CarotidFlowGlyphs.cxx )
      target_link_libraries(CarotidFlowGlyphs PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(CarotidFlowGlyphs MACOSX_BUNDLE CarotidFlowGlyphs.cxx )
      target_link_libraries(CarotidFlowGlyphs PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS CarotidFlowGlyphs
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build CarotidFlowGlyphs

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

    cd CarotidFlowGlyphs/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:

    ./CarotidFlowGlyphs

WINDOWS USERS

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