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# ImageGaussianSmooth

VTKEx/Cxx/Images/ImageGaussianSmooth

Question

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### Code

ImageGaussianSmooth.cxx

    #include <vtkSmartPointer.h>
    #include <vtkImageData.h>
    #include <vtkImageMapper3D.h>
    #include <vtkImageGaussianSmooth.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkInteractorStyleImage.h>
    #include <vtkRenderer.h>
    #include <vtkImageActor.h>
    #include <vtkImageEllipsoidSource.h>
    #include <vtkImageCast.h>

    int main(int, char *[])
    {
      // Create an image
      vtkSmartPointer<vtkImageEllipsoidSource> source =
        vtkSmartPointer<vtkImageEllipsoidSource>::New();
      source->SetWholeExtent(0, 20, 0, 20, 0, 0);
      source->SetCenter(10,10,0);
      source->SetRadius(3,4,0);
      source->Update();

      vtkSmartPointer<vtkImageGaussianSmooth> gaussianSmoothFilter =
        vtkSmartPointer<vtkImageGaussianSmooth>::New();
      gaussianSmoothFilter->SetInputConnection(source->GetOutputPort());
      gaussianSmoothFilter->Update();

      // Create actors
      vtkSmartPointer<vtkImageActor> originalActor =
        vtkSmartPointer<vtkImageActor>::New();
      originalActor->GetMapper()->SetInputConnection(source->GetOutputPort());

      vtkSmartPointer<vtkImageActor> smoothedActor =
        vtkSmartPointer<vtkImageActor>::New();
      smoothedActor->GetMapper()->SetInputConnection(
        gaussianSmoothFilter->GetOutputPort());

       // Define viewport ranges
      // (xmin, ymin, xmax, ymax)
      double originalViewport[4] = {0.0, 0.0, 0.5, 1.0};
      double smoothedViewport[4] = {0.5, 0.0, 1.0, 1.0};

      // Setup renderers
      vtkSmartPointer<vtkRenderer> originalRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      originalRenderer->SetViewport(originalViewport);
      originalRenderer->AddActor(originalActor);
      originalRenderer->ResetCamera();
      originalRenderer->SetBackground(.4, .5, .6);

      vtkSmartPointer<vtkRenderer> gradientMagnitudeRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      gradientMagnitudeRenderer->SetViewport(smoothedViewport);
      gradientMagnitudeRenderer->AddActor(smoothedActor);
      gradientMagnitudeRenderer->ResetCamera();
      gradientMagnitudeRenderer->SetBackground(.4, .5, .7);

      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(600, 300);
      renderWindow->AddRenderer(originalRenderer);
      renderWindow->AddRenderer(gradientMagnitudeRenderer);

      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      vtkSmartPointer<vtkInteractorStyleImage> style =
        vtkSmartPointer<vtkInteractorStyleImage>::New();

      renderWindowInteractor->SetInteractorStyle(style);

      renderWindowInteractor->SetRenderWindow(renderWindow);
      renderWindow->Render();
      renderWindowInteractor->Initialize();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ImageGaussianSmooth)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkImagingCore
      vtkImagingGeneral
      vtkImagingSources
      vtkInteractionStyle
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping ImageGaussianSmooth: ${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(ImageGaussianSmooth MACOSX_BUNDLE ImageGaussianSmooth.cxx )
      target_link_libraries(ImageGaussianSmooth PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(ImageGaussianSmooth MACOSX_BUNDLE ImageGaussianSmooth.cxx )
      target_link_libraries(ImageGaussianSmooth PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS ImageGaussianSmooth
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build ImageGaussianSmooth

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

    cd ImageGaussianSmooth/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:

    ./ImageGaussianSmooth

WINDOWS USERS

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