Skip to content


# SignedDistance

VTKEx/Cxx/Points/SignedDistance

### Description

Contrast this with the UnsignedDistance example.

The image was created using the Armadillo dataset

Warning

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

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

### Code

SignedDistance.cxx

    #include <vtkCamera.h>
    #include <vtkImageActor.h>
    #include <vtkImageData.h>
    #include <vtkImageMapToColors.h>
    #include <vtkImageMapper3D.h>
    #include <vtkLookupTable.h>
    #include <vtkPCANormalEstimation.h>
    #include <vtkPointSource.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkScalarBarActor.h>
    #include <vtkSignedDistance.h>
    #include <vtkSmartPointer.h>

    // Readers
    #include <vtkBYUReader.h>
    #include <vtkOBJReader.h>
    #include <vtkPLYReader.h>
    #include <vtkPolyDataReader.h>
    #include <vtkSTLReader.h>
    #include <vtkXMLPolyDataReader.h>

    #include <vtkPointSource.h>
    #include <vtkPolyData.h>

    #include <algorithm> // For transform()
    #include <cctype>    // For to_lower
    #include <string>    // For find_last_of()

    namespace {
    vtkSmartPointer<vtkPolyData> ReadPolyData(std::string const& fileName);
    }

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

      double bounds[6];
      polyData->GetBounds(bounds);
      double range[3];
      for (int i = 0; i < 3; ++i)
      {
        range[i] = bounds[2 * i + 1] - bounds[2 * i];
      }

      int sampleSize = polyData->GetNumberOfPoints() * .00005;
      if (sampleSize < 10)
      {
        sampleSize = 10;
      }
      std::cout << "Sample size is: " << sampleSize << std::endl;
      auto normals = vtkSmartPointer<vtkPCANormalEstimation>::New();
      normals->SetInputData(polyData);
      normals->SetSampleSize(sampleSize);
      normals->SetNormalOrientationToGraphTraversal();
      normals->FlipNormalsOn();
      std::cout << "Range: " << range[0] << ", " << range[1] << ", " << range[2]
                << std::endl;
      int dimension = 256;
      dimension = 128;
      // auto radius = range[0] * .02;
      auto radius = range[0] / static_cast<double>(dimension) * 5; // ~5 voxels
      std::cout << "Radius: " << radius << std::endl;
      auto distance = vtkSmartPointer<vtkSignedDistance>::New();
      distance->SetInputConnection(normals->GetOutputPort());
      distance->SetRadius(radius);
      distance->SetDimensions(dimension, dimension, dimension);
      distance->SetBounds(bounds[0] - range[0] * .1, bounds[1] + range[0] * .1,
                          bounds[2] - range[1] * .1, bounds[3] + range[1] * .1,
                          bounds[4] - range[2] * .1, bounds[5] + range[2] * .1);

      // Create a lookup table that consists of the full hue circle
      // (from HSV).
      auto hueLut = vtkSmartPointer<vtkLookupTable>::New();
      hueLut->SetTableRange(-.99 * radius, .99 * radius);
      hueLut->SetHueRange(.667, 0);
      hueLut->SetSaturationRange(1, 1);
      hueLut->SetValueRange(1, 1);
      hueLut->UseBelowRangeColorOn();
      hueLut->SetBelowRangeColor(0, 0, 0, 0);
      hueLut->UseAboveRangeColorOn();
      hueLut->SetAboveRangeColor(0, 0, 0, 0);
      hueLut->SetNumberOfColors(5);
      hueLut->Build();
      double* last = hueLut->GetTableValue(4);
      hueLut->SetAboveRangeColor(last[0], last[1], last[2], 0);

      auto sagittalColors = vtkSmartPointer<vtkImageMapToColors>::New();
      sagittalColors->SetInputConnection(distance->GetOutputPort());
      sagittalColors->SetLookupTable(hueLut);
      sagittalColors->Update();

      auto sagittal = vtkSmartPointer<vtkImageActor>::New();
      sagittal->GetMapper()->SetInputConnection(sagittalColors->GetOutputPort());
      sagittal->SetDisplayExtent(dimension / 2, dimension / 2, 0, dimension - 1, 0,
                                 dimension - 1);
      sagittal->ForceOpaqueOn();

      auto axialColors = vtkSmartPointer<vtkImageMapToColors>::New();
      axialColors->SetInputConnection(distance->GetOutputPort());
      axialColors->SetLookupTable(hueLut);
      axialColors->Update();

      auto axial = vtkSmartPointer<vtkImageActor>::New();
      axial->GetMapper()->SetInputConnection(axialColors->GetOutputPort());
      axial->SetDisplayExtent(0, dimension - 1, 0, dimension - 1, dimension / 2,
                              dimension / 2);
      axial->ForceOpaqueOn();

      auto coronalColors = vtkSmartPointer<vtkImageMapToColors>::New();
      coronalColors->SetInputConnection(distance->GetOutputPort());
      coronalColors->SetLookupTable(hueLut);
      coronalColors->Update();

      auto coronal = vtkSmartPointer<vtkImageActor>::New();
      coronal->GetMapper()->SetInputConnection(coronalColors->GetOutputPort());
      coronal->SetDisplayExtent(0, dimension - 1, dimension / 2, dimension / 2, 0,
                                dimension - 1);
      coronal->ForceOpaqueOn();

      // Create a scalar bar
      auto scalarBar = vtkSmartPointer<vtkScalarBarActor>::New();
      scalarBar->SetLookupTable(hueLut);
      scalarBar->SetTitle("Distance");
      scalarBar->SetNumberOfLabels(5);

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

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

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

      // Add the actors to the renderer, set the background and size
      //
      ren1->AddActor(sagittal);
      ren1->AddActor(axial);
      ren1->AddActor(coronal);
      ren1->AddActor2D(scalarBar);

      // Generate an interesting view
      //
      ren1->ResetCamera();
      ren1->GetActiveCamera()->Azimuth(120);
      ren1->GetActiveCamera()->Elevation(30);
      ren1->GetActiveCamera()->Dolly(1.5);
      ren1->ResetCameraClippingRange();

      renWin->Render();
      iren->Initialize();
      iren->Start();
      std::cout << distance->GetOutput()->GetScalarRange()[0] << ", "
                << distance->GetOutput()->GetScalarRange()[1] << std::endl;
      return EXIT_SUCCESS;
    }

    namespace {
    vtkSmartPointer<vtkPolyData> ReadPolyData(std::string const& fileName)
    {
      vtkSmartPointer<vtkPolyData> polyData;
      std::string extension = "";
      if (fileName.find_last_of(".") != std::string::npos)
      {
        extension = fileName.substr(fileName.find_last_of("."));
      }
      // Make the extension lowercase
      std::transform(extension.begin(), extension.end(), extension.begin(),
                     ::tolower);
      if (extension == ".ply")
      {
        auto reader = vtkSmartPointer<vtkPLYReader>::New();
        reader->SetFileName(fileName.c_str());
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtp")
      {
        auto reader = vtkSmartPointer<vtkXMLPolyDataReader>::New();
        reader->SetFileName(fileName.c_str());
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".obj")
      {
        auto reader = vtkSmartPointer<vtkOBJReader>::New();
        reader->SetFileName(fileName.c_str());
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".stl")
      {
        auto reader = vtkSmartPointer<vtkSTLReader>::New();
        reader->SetFileName(fileName.c_str());
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtk")
      {
        auto reader = vtkSmartPointer<vtkPolyDataReader>::New();
        reader->SetFileName(fileName.c_str());
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".g")
      {
        auto reader = vtkSmartPointer<vtkBYUReader>::New();
        reader->SetGeometryFileName(fileName.c_str());
        reader->Update();
        polyData = reader->GetOutput();
      }
      else
      {
        auto points = vtkSmartPointer<vtkPointSource>::New();
        points->SetNumberOfPoints(100000);
        points->SetRadius(10.0);
        points->SetCenter(vtkMath::Random(-100, 100), vtkMath::Random(-100, 100),
                          vtkMath::Random(-100, 100));
        points->SetDistributionToShell();
        points->Update();
        polyData = points->GetOutput();
      }
      return polyData;
    }

    } // namespace

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(SignedDistance)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersPoints
      vtkFiltersSources
      vtkIOGeometry
      vtkIOLegacy
      vtkIOPLY
      vtkIOXML
      vtkImagingCore
      vtkInteractionStyle
      vtkRenderingAnnotation
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping SignedDistance: ${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(SignedDistance MACOSX_BUNDLE SignedDistance.cxx )
      target_link_libraries(SignedDistance PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(SignedDistance MACOSX_BUNDLE SignedDistance.cxx )
      target_link_libraries(SignedDistance PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS SignedDistance
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build SignedDistance

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

    cd SignedDistance/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:

    ./SignedDistance

WINDOWS USERS

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