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FlyingHeadSlice

vtk-examples/Cxx/VisualizationAlgorithms/FlyingHeadSlice

Description

This example generates 2D contour lines on one CT slice through the head. The contours correspond to density values of the tissues and are colored according to density value.

This example is a modification of HeadSlice using vtkFlyingEdges2D for contouring. However there is an option to use vtkContourFilter instead.

Info

See Figure 6-11a in Chapter 6 of the VTK Textbook.

Other languages

See (Python)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

FlyingHeadSlice.cxx

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkContourFilter.h>
#include <vtkExtractVOI.h>
#include <vtkFlyingEdges2D.h>
#include <vtkMetaImageReader.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkOutlineFilter.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

#include <array>
#include <iostream>
#include <string>

int main(int argc, char* argv[])
{
  if (argc < 2)
  {
    std::cout << "Generate 2D contour lines, corresponding to tissue density, "
                 "on one CT slice through the head."
              << std::endl;
    std::cout << "The contour lines are colored by the tissue density."
              << std::endl;
    std::cout << "Usage: " << argv[0] << " FullHead.mhd [useContourFilter]"
              << std::endl;
    std::cout << "where: filename is FullHead.mhd," << std::endl;
    std::cout << "       useContourFilter = 0|1" << std::endl;
    std::cout << "Examples:" << std::endl;
    std::cout << "Contouring, using vtkFlyingEdges2D: FullHead.mhd"
              << std::endl;
    std::cout << "Contouring, using vtkContourFilter: FullHead.mhd 1"
              << std::endl;
    return EXIT_FAILURE;
  }
  auto useContourFilter = false;
  if (argc > 2)
  {
    if (atoi(argv[2]) != 0)
    {
      useContourFilter = true;
    }
  }

  if (useContourFilter)
  {
    std::cout << "Using vtkContourFilter." << std::endl;
  }
  else
  {
    std::cout << "Using vtkFlyingEdges2D." << std::endl;
  }

  vtkNew<vtkNamedColors> colors;

  // Create the RenderWindow, Renderer and both Actors.
  vtkNew<vtkRenderer> ren1;
  vtkNew<vtkRenderWindow> renWin;
  renWin->AddRenderer(ren1);
  vtkNew<vtkRenderWindowInteractor> iren;
  iren->SetRenderWindow(renWin);

  // Create the pipeline.
  vtkNew<vtkMetaImageReader> reader;
  reader->SetFileName(argv[1]);
  reader->Update();

  vtkNew<vtkExtractVOI> extractVOI;
  extractVOI->SetInputConnection(reader->GetOutputPort());
  extractVOI->SetVOI(0, 255, 0, 255, 45, 45);
  extractVOI->Update();
  // double* scalarRange = extractVOI->GetOutput()->GetScalarRange();
  std::array<double, 2> scalarRange = {{500, 1150}};
  // std::cout << scalarRange[0] << ", " << scalarRange[1] << std::endl;

  vtkNew<vtkContourFilter> contour;
  vtkNew<vtkFlyingEdges2D> flyingEdges;
  vtkNew<vtkPolyDataMapper> isoMapper;
  if (useContourFilter)
  {
    contour->SetInputConnection(extractVOI->GetOutputPort());
    contour->GenerateValues(12, scalarRange.data());
    isoMapper->SetInputConnection(contour->GetOutputPort());
  }
  else
  {
    flyingEdges->SetInputConnection(extractVOI->GetOutputPort());
    flyingEdges->GenerateValues(12, scalarRange.data());
    isoMapper->SetInputConnection(flyingEdges->GetOutputPort());
  }
  isoMapper->ScalarVisibilityOn();
  isoMapper->SetScalarRange(scalarRange.data());

  vtkNew<vtkActor> isoActor;
  isoActor->SetMapper(isoMapper);
  isoActor->GetProperty()->SetColor(colors->GetColor3d("Wheat").GetData());

  vtkNew<vtkOutlineFilter> outline;
  outline->SetInputConnection(extractVOI->GetOutputPort());

  vtkNew<vtkPolyDataMapper> outlineMapper;
  outlineMapper->SetInputConnection(outline->GetOutputPort());

  vtkNew<vtkActor> outlineActor;
  outlineActor->SetMapper(outlineMapper);

  // Add the actors to the renderer, set the background and size.
  ren1->AddActor(outlineActor);
  ren1->AddActor(isoActor);
  ren1->SetBackground(colors->GetColor3d("SlateGray").GetData());
  ren1->ResetCamera();
  ren1->GetActiveCamera()->Dolly(1.5);
  ren1->ResetCameraClippingRange();

  renWin->SetSize(640, 640);
  renWin->SetWindowName("FlyingHeadSlice");
  renWin->Render();

  iren->Start();
  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(FlyingHeadSlice)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "FlyingHeadSlice: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(FlyingHeadSlice MACOSX_BUNDLE FlyingHeadSlice.cxx )
  target_link_libraries(FlyingHeadSlice PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS FlyingHeadSlice
  MODULES ${VTK_LIBRARIES}
)

Download and Build FlyingHeadSlice

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

cd FlyingHeadSlice/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:

./FlyingHeadSlice

WINDOWS USERS

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