# FrogSlice

VTKExamples/Cxx/Visualization/FrogSlice

This example uses a dataset derived from a frog. This data was prepared at Lawrence Berkeley National Laboratories and is included with their permission. The data was acquired by physically slicing the frog and photographing the slices. The original segmented data is in the form of tissue masks with one file per tissue. There are 136 slices per tissue and 15 different tissues. Each slice is 470 by 500 pixels. (To accommodate the volume readers we have in VTK, we processed the mask files and combined them all into one vtkMetaImageReader .mhd file. Integer numbers 1–15 to represent the 15 tissues.

This example shows a photographic slice of frog (upper left), segmented frog (upper right) and composite of photo and segmentation (bottom). The purple color represents the stomach and the kidneys are yellow.

### Code

FrogSlice.cxx

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkImageConstantPad.h>
    #include <vtkLookupTable.h>
    #include <vtkMetaImageReader.h>
    #include <vtkNamedColors.h>
    #include <vtkPlaneSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkPolyDataNormals.h>
    #include <vtkProperty.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkTexture.h>
    #include <vtkTransform.h>
    #include <vtkTransformPolyDataFilter.h>
    #include <vtkWindowLevelLookupTable.h>

    #include <map>
    #include <string>

    namespace
    {
    void CreateFrogLut(vtkSmartPointer<vtkLookupTable> &colorLut);
    void SliceOrder(std::map<std::string,
                    vtkSmartPointer<vtkTransform> > &sliceOrder);
    }
    int main (int argc, char *argv[])
    {
      if (argc < 3)
      {
        std::cout << "Usage: " << argv[0] << " frog.mhd frogtissue.mhd [slice]" << std::endl;
        return EXIT_FAILURE;
      }
      int sliceNumber = 39; // to match figure 12-6
      if (argc > 3)
      {
        sliceNumber = atoi(argv[3]);
      }
      std::map<std::string, vtkSmartPointer<vtkTransform> > sliceOrder;
      SliceOrder(sliceOrder);

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

    // Now create the RenderWindow, Renderer and Interactor
    //
      vtkSmartPointer<vtkRenderer> ren1 =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderer> ren2 =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderer> ren3 =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->AddRenderer(ren1);
      renWin->AddRenderer(ren2);
      renWin->AddRenderer(ren3);

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

      vtkSmartPointer<vtkMetaImageReader> greyReader =
        vtkSmartPointer<vtkMetaImageReader>::New();
      greyReader->SetFileName(argv[1]);
      greyReader->Update();

      vtkSmartPointer<vtkImageConstantPad> greyPadder =
        vtkSmartPointer<vtkImageConstantPad>::New();
      greyPadder->SetInputConnection(greyReader->GetOutputPort());
      greyPadder->SetOutputWholeExtent(0, 511, 0, 511, sliceNumber, sliceNumber);
      greyPadder->SetConstant(0);

      vtkSmartPointer<vtkPlaneSource> greyPlane =
        vtkSmartPointer<vtkPlaneSource>::New();

      vtkSmartPointer<vtkTransformPolyDataFilter> greyTransform =
        vtkSmartPointer<vtkTransformPolyDataFilter>::New();
      greyTransform->SetTransform(sliceOrder["hfsi"]);
      greyTransform->SetInputConnection(greyPlane->GetOutputPort());

      vtkSmartPointer<vtkPolyDataNormals> greyNormals =
        vtkSmartPointer<vtkPolyDataNormals>::New();
      greyNormals->SetInputConnection(greyTransform->GetOutputPort());
      greyNormals->FlipNormalsOff();

      vtkSmartPointer<vtkWindowLevelLookupTable> wllut =
        vtkSmartPointer<vtkWindowLevelLookupTable>::New();
      wllut->SetWindow(255);
      wllut->SetLevel(128);
      wllut->SetTableRange(0, 255);
      wllut->Build();

      vtkSmartPointer<vtkPolyDataMapper> greyMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      greyMapper->SetInputConnection(greyPlane->GetOutputPort());

      vtkSmartPointer<vtkTexture> greyTexture =
        vtkSmartPointer<vtkTexture>::New();
      greyTexture->SetInputConnection(greyPadder->GetOutputPort());
      greyTexture->SetLookupTable(wllut);
      greyTexture->SetColorModeToMapScalars();
      greyTexture->InterpolateOn();

      vtkSmartPointer<vtkActor> greyActor =
        vtkSmartPointer<vtkActor>::New();
      greyActor->SetMapper(greyMapper);
      greyActor->SetTexture(greyTexture);

      vtkSmartPointer<vtkMetaImageReader> segmentReader =
        vtkSmartPointer<vtkMetaImageReader>::New();
      segmentReader->SetFileName(argv[2]);
      segmentReader->Update();

      vtkSmartPointer<vtkImageConstantPad> segmentPadder =
        vtkSmartPointer<vtkImageConstantPad>::New();
      segmentPadder->SetInputConnection(segmentReader->GetOutputPort());
      segmentPadder->SetOutputWholeExtent(0, 511, 0, 511, sliceNumber, sliceNumber);
      segmentPadder->SetConstant(0);

      vtkSmartPointer<vtkPlaneSource> segmentPlane =
        vtkSmartPointer<vtkPlaneSource>::New();

      vtkSmartPointer<vtkTransformPolyDataFilter> segmentTransform =
        vtkSmartPointer<vtkTransformPolyDataFilter>::New();
      segmentTransform->SetTransform(sliceOrder["hfsi"]);
      segmentTransform->SetInputConnection(segmentPlane->GetOutputPort());

      vtkSmartPointer<vtkPolyDataNormals> segmentNormals =
        vtkSmartPointer<vtkPolyDataNormals>::New();
      segmentNormals->SetInputConnection(segmentTransform->GetOutputPort());
      segmentNormals->FlipNormalsOn();

      vtkSmartPointer<vtkLookupTable> colorLut =
        vtkSmartPointer<vtkLookupTable>::New();
      colorLut->SetNumberOfColors(17);
      colorLut->SetTableRange(0, 16);
      colorLut->Build();
      CreateFrogLut(colorLut);

      vtkSmartPointer<vtkPolyDataMapper> segmentMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      segmentMapper->SetInputConnection(segmentPlane->GetOutputPort());

      vtkSmartPointer<vtkTexture> segmentTexture =
        vtkSmartPointer<vtkTexture>::New();
      segmentTexture->SetInputConnection(segmentPadder->GetOutputPort());
      segmentTexture->SetLookupTable(colorLut);
      segmentTexture->SetColorModeToMapScalars();
      segmentTexture->InterpolateOff();

      vtkSmartPointer<vtkActor> segmentActor =
        vtkSmartPointer<vtkActor>::New();
      segmentActor->SetMapper(segmentMapper);
      segmentActor->SetTexture(segmentTexture);

      vtkSmartPointer<vtkActor> segmentOverlayActor =
        vtkSmartPointer<vtkActor>::New();
      segmentOverlayActor->SetMapper(segmentMapper);
      segmentOverlayActor->SetTexture(segmentTexture);

      segmentOverlayActor->GetProperty()->SetOpacity(.5);
      ren1->SetBackground(0, 0, 0);
      ren1->SetViewport(0, .5, .5, 1);
      renWin->SetSize(640, 480);
      ren1->AddActor(greyActor);

      ren2->SetBackground(0, 0,0);
      ren2->SetViewport(.5, .5, 1, 1);
      ren2->AddActor(segmentActor);

      vtkSmartPointer<vtkCamera> cam1 =
        vtkSmartPointer<vtkCamera>::New();
      cam1->SetViewUp(0, -1, 0);
      cam1->SetPosition(0, 0, -1);
      ren1->SetActiveCamera(cam1);
      ren1->ResetCamera();
      cam1->SetViewUp(0, -1, 0);
      cam1->SetPosition(0.0554068, -0.0596001, -0.491383);
      cam1->SetFocalPoint(0.0554068, -0.0596001, 0);
      ren1->ResetCameraClippingRange();

      ren3->AddActor(greyActor);
      ren3->AddActor(segmentOverlayActor);
      segmentOverlayActor->SetPosition(0, 0, -.01);

      ren3->SetBackground(0, 0, 0);
      ren3->SetViewport(0, 0, 1, .5);

      ren2->SetActiveCamera(ren1->GetActiveCamera());
      ren3->SetActiveCamera(ren1->GetActiveCamera());

      renWin->Render();
      iren->Start();

      return EXIT_SUCCESS;
    }

    namespace
    {
    void CreateFrogLut(vtkSmartPointer<vtkLookupTable> &colorLut)
    {
      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();
      colorLut->SetTableValue(0,
                              0, 0, 0, 0);
      colorLut->SetTableValue(1,
                              colors->GetColor4d("salmon").GetData()); //blood
      colorLut->SetTableValue(2,
                              colors->GetColor4d("beige").GetData()); //brain
      colorLut->SetTableValue(3,
                              colors->GetColor4d("orange").GetData()); //duodenum
      colorLut->SetTableValue(4,
                              colors->GetColor4d("misty_rose").GetData()); //eye_retina
      colorLut->SetTableValue(5,
                              colors->GetColor4d("white").GetData()); //eye_white
      colorLut->SetTableValue(6,
                              colors->GetColor4d("tomato").GetData()); //heart
      colorLut->SetTableValue(7,
                              colors->GetColor4d("raspberry").GetData()); //ileum
      colorLut->SetTableValue(8,
                              colors->GetColor4d("banana").GetData()); //kidney
      colorLut->SetTableValue(9,
                              colors->GetColor4d("peru").GetData()); //l_intestine
      colorLut->SetTableValue(10,
                              colors->GetColor4d("pink").GetData()); //liver
      colorLut->SetTableValue(11,
                              colors->GetColor4d("powder_blue").GetData()); //lung
      colorLut->SetTableValue(12,
                              colors->GetColor4d("carrot").GetData()); //nerve
      colorLut->SetTableValue(13,
                              colors->GetColor4d("wheat").GetData()); //skeleton
      colorLut->SetTableValue(14,
                              colors->GetColor4d("violet").GetData()); //spleen
      colorLut->SetTableValue(15,
                              colors->GetColor4d("plum").GetData()); //stomach
    }

    void SliceOrder(std::map<std::string, vtkSmartPointer<vtkTransform> > &sliceOrder)
    {
    //
    // these transformations permute medical image data to maintain proper orientation
    // regardless of the acquisition order. After applying these transforms with
    // vtkTransformFilter, a view up of 0,-1,0 will result in the body part
    // facing the viewer.
    // NOTE: some transformations have a -1 scale factor for one of the components.
    //       To ensure proper polygon orientation and normal direction, you must
    //       apply the vtkPolyDataNormals filter.
    //
    // Naming:
    // si - superior to inferior (top to bottom)
    // is - inferior to superior (bottom to top)
    // ap - anterior to posterior (front to back)
    // pa - posterior to anterior (back to front)
    // lr - left to right
    // rl - right to left
    //
      double siMatrix[16] = {1, 0, 0, 0,  0, 0, 1, 0,  0, -1, 0, 0,  0, 0, 0, 1};
      vtkSmartPointer<vtkTransform> si =
        vtkSmartPointer<vtkTransform>::New();
      si->SetMatrix(siMatrix);
      sliceOrder["si"] = si;

      double isMatrix[16] = {1, 0, 0, 0,  0, 0, -1, 0,  0, -1, 0, 0,  0, 0, 0, 1};
      vtkSmartPointer<vtkTransform> is =
        vtkSmartPointer<vtkTransform>::New();
      is->SetMatrix(isMatrix);
      sliceOrder["is"] = is;

      vtkSmartPointer< vtkTransform> ap =
        vtkSmartPointer<vtkTransform>::New();
      ap->Scale(1, -1, 1);
      sliceOrder["ap"] = ap;

      vtkSmartPointer<vtkTransform> pa =
        vtkSmartPointer<vtkTransform>::New();
      pa->Scale(1, -1, -1);
      sliceOrder["pa"] = pa;

      double lrMatrix[16] = {0,0,-1,0, 0,-1,0,0, 1,0,0,0, 0, 0, 0, 1};
      vtkSmartPointer<vtkTransform> lr =
        vtkSmartPointer<vtkTransform>::New();
      lr->SetMatrix(lrMatrix);
      sliceOrder["lr"] = lr;

      double rlMatrix[16] = {0, 0, 1, 0,  0, -1, 0, 0,  1, 0, 0, 0,  0, 0, 0, 1};
      vtkSmartPointer<vtkTransform> rl =
        vtkSmartPointer<vtkTransform>::New();
      rl->SetMatrix(rlMatrix);
      sliceOrder["rl"] = rl;

    //
    // The previous transforms assume radiological views of the slices (viewed from the feet). other
    // modalities such as physical sectioning may view from the head. these transforms modify the original
    // with a 180 rotation about y
    //
      double hfMatrix[16] = { -1, 0, 0, 0,  0, 1, 0, 0,  0, 0, -1, 0,  0, 0, 0, 1};
      vtkSmartPointer<vtkTransform> hf =
        vtkSmartPointer<vtkTransform>::New();
      hf->SetMatrix(hfMatrix);
      sliceOrder["hf"] = hf;

      vtkSmartPointer<vtkTransform> hfsi =
        vtkSmartPointer<vtkTransform>::New();
      hfsi->Concatenate(hf->GetMatrix());
      hfsi->Concatenate(si->GetMatrix());
      sliceOrder["hfsi"] = hfsi;

      vtkSmartPointer<vtkTransform> hfis =
        vtkSmartPointer<vtkTransform>::New();
      hfis->Concatenate(hf->GetMatrix());
      hfis->Concatenate(is->GetMatrix());
      sliceOrder["hfis"] = hfis;

      vtkSmartPointer<vtkTransform> hfap =
        vtkSmartPointer<vtkTransform>::New();
      hfap->Concatenate(hf->GetMatrix());
      hfap->Concatenate(ap->GetMatrix());
      sliceOrder["hfap"] = hfap;

      vtkSmartPointer<vtkTransform> hfpa =
        vtkSmartPointer<vtkTransform>::New();
      hfpa->Concatenate(hf->GetMatrix());
      hfpa->Concatenate(pa->GetMatrix());
      sliceOrder["hfpa"] = hfpa;

      vtkSmartPointer<vtkTransform> hflr =
        vtkSmartPointer<vtkTransform>::New();
      hflr->Concatenate(hf->GetMatrix());
      hflr->Concatenate(lr->GetMatrix());
      sliceOrder[""] = hflr;

      vtkSmartPointer<vtkTransform> hfrl =
        vtkSmartPointer<vtkTransform>::New();
      hfrl->Concatenate(hf->GetMatrix());
      hfrl->Concatenate(rl->GetMatrix());
      sliceOrder["hfrl"] = hfrl;
        }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(FrogSlice)

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

    add_executable(FrogSlice MACOSX_BUNDLE FrogSlice.cxx )

    target_link_libraries(FrogSlice ${VTK_LIBRARIES})

### Download and Build FrogSlice

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

    cd FrogSlice/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:

    ./FrogSlice

WINDOWS USERS

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