# SmoothDiscreteMarchingCubes

VTKExamples/Cxx/Modelling/SmoothDiscreteMarchingCubes

### Description

Creates surfaces from labelled data. Volume data does not always contain samples of continuous data. A volume may contain discrete integer values, often the result of segmentation. This example smooths the discrete models generated by vtkDiscreteMarchingCubes with vtkWindowedSincPolyDataFilter.

Seealso

DiscreteMarchingCubes produces rough models.

### Code

SmoothDiscreteMarchingCubes.cxx

    #include <vtkSmartPointer.h>
    #include <vtkDiscreteMarchingCubes.h>
    #include <vtkWindowedSincPolyDataFilter.h>

    #include <vtkMath.h>
    #include <vtkImageData.h>
    #include <vtkSphere.h>
    #include <vtkSampleFunction.h>
    #include <vtkImageThreshold.h>
    #include <vtkImageMathematics.h>
    #include <vtkPolyDataMapper.h>

    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkActor.h>
    #include <vtkLookupTable.h>

    #include <vtkNamedColors.h>

    static vtkSmartPointer<vtkLookupTable> MakeColors (unsigned int n);
    static vtkSmartPointer<vtkImageData> MakeBlob(int n, double radius);

    int main (int /* argc */, char * /* argv */ [])
    {
      int n = 20;
      double radius = 8;

      vtkSmartPointer<vtkImageData> blob = MakeBlob(n, radius);

      vtkSmartPointer<vtkDiscreteMarchingCubes> discrete =
        vtkSmartPointer<vtkDiscreteMarchingCubes>::New();
      discrete->SetInputData(blob);
      discrete->GenerateValues(n, 1, n);

      unsigned int smoothingIterations = 15;
      double passBand = 0.001;
      double featureAngle = 120.0;

      vtkSmartPointer<vtkWindowedSincPolyDataFilter> smoother =
        vtkSmartPointer<vtkWindowedSincPolyDataFilter>::New();
      smoother->SetInputConnection(discrete->GetOutputPort());
      smoother->SetNumberOfIterations(smoothingIterations);
      smoother->BoundarySmoothingOff();
      smoother->FeatureEdgeSmoothingOff();
      smoother->SetFeatureAngle(featureAngle);
      smoother->SetPassBand(passBand);
      smoother->NonManifoldSmoothingOn();
      smoother->NormalizeCoordinatesOn();
      smoother->Update();

      vtkSmartPointer<vtkLookupTable> lut = MakeColors(n);

      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(smoother->GetOutputPort());
      mapper->SetLookupTable(lut);
      mapper->SetScalarRange(0, lut->GetNumberOfColors());

    // Create the RenderWindow, Renderer and both Actors
    //
      vtkSmartPointer<vtkRenderer> ren1 =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->AddRenderer(ren1);
      vtkSmartPointer<vtkRenderWindowInteractor> iren =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      iren->SetRenderWindow(renWin);

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);

      ren1->AddActor(actor);

      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();
      ren1->SetBackground(colors->GetColor3d("Burlywood").GetData());

      renWin->Render();

      iren->Start();

      return EXIT_SUCCESS;
    }

    vtkSmartPointer<vtkImageData> MakeBlob(int n, double radius)
    {
      vtkSmartPointer<vtkMath> math =
        vtkSmartPointer<vtkMath>::New();

      vtkSmartPointer<vtkImageData> blobImage =
        vtkSmartPointer<vtkImageData>::New();

      for (int i = 0; i < n; ++i)
      {
        vtkSmartPointer<vtkSphere> sphere =
          vtkSmartPointer<vtkSphere>::New();
        sphere->SetRadius(radius);
        double maxR = 50 - 2.0 * radius;
        sphere->SetCenter(int(math->Random(-maxR, maxR)),
                          int(math->Random(-maxR, maxR)), int(math->Random(-maxR, maxR)));

        vtkSmartPointer<vtkSampleFunction> sampler =
          vtkSmartPointer<vtkSampleFunction>::New();
        sampler->SetImplicitFunction(sphere);
        sampler->SetOutputScalarTypeToFloat();
        sampler->SetSampleDimensions(100, 100, 100);
        sampler->SetModelBounds(-50, 50, -50, 50, -50, 50);

        vtkSmartPointer<vtkImageThreshold> thres =
          vtkSmartPointer<vtkImageThreshold>::New();
        thres->SetInputConnection(sampler->GetOutputPort());
        thres->ThresholdByLower(radius * radius);
        thres->ReplaceInOn();
        thres->ReplaceOutOn();
        thres->SetInValue(i + 1);
        thres->SetOutValue(0);
        thres->Update();
        if (i == 0)
        {
          blobImage->DeepCopy(thres->GetOutput());
        }

        vtkSmartPointer<vtkImageMathematics>     maxValue =
          vtkSmartPointer<vtkImageMathematics>::New();
        maxValue->SetInputData(0, blobImage);
        maxValue->SetInputData(1, thres->GetOutput());
        maxValue->SetOperationToMax();
        maxValue->Modified();
        maxValue->Update();

        blobImage->DeepCopy(maxValue->GetOutput());
      }
      return blobImage;
    }

    // Generate some random colors
    vtkSmartPointer<vtkLookupTable> MakeColors (unsigned int n)
    {
      vtkSmartPointer<vtkLookupTable> lut =
        vtkSmartPointer<vtkLookupTable>::New();
      lut->SetNumberOfColors(n);
      lut->SetTableRange(0, n - 1);
      lut->SetScaleToLinear();
      lut->Build();
      lut->SetTableValue(0, 0, 0, 0, 1);

      vtkSmartPointer<vtkMath> math =
        vtkSmartPointer<vtkMath>::New();
      math->RandomSeed(5071);
      for ( int i = 1; i < static_cast<int>(n); ++i)
      {
        lut->SetTableValue(i, math->Random(.4, 1),
                           math->Random(.4, 1), math->Random(.4, 1), 1.0);
      }
      return lut;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(SmoothDiscreteMarchingCubes)

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

    add_executable(SmoothDiscreteMarchingCubes MACOSX_BUNDLE SmoothDiscreteMarchingCubes.cxx )

    target_link_libraries(SmoothDiscreteMarchingCubes ${VTK_LIBRARIES})

### Download and Build SmoothDiscreteMarchingCubes

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

    cd SmoothDiscreteMarchingCubes/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:

    ./SmoothDiscreteMarchingCubes

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.