ImageVariance3D

#include <vtkImageActor.h>
#include <vtkImageCast.h>
#include <vtkImageEllipsoidSource.h>
#include <vtkImageMapper3D.h>
#include <vtkImageVariance3D.h>
#include <vtkInteractorStyleImage.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // Create an image.
  vtkNew<vtkImageEllipsoidSource> source;
  source->SetWholeExtent(0, 20, 0, 20, 0, 0);
  source->SetCenter(10, 10, 0);
  source->SetRadius(3, 4, 0);
  source->Update();

  vtkNew<vtkImageVariance3D> varianceFilter;
  varianceFilter->SetInputConnection(source->GetOutputPort());
  varianceFilter->SetKernelSize(5, 4, 3);
  varianceFilter->Update();

  vtkNew<vtkImageCast> varianceCastFilter;
  varianceCastFilter->SetOutputScalarTypeToFloat();
  varianceCastFilter->SetInputConnection(varianceFilter->GetOutputPort());
  varianceCastFilter->Update();

  // Create actors.
  vtkNew<vtkImageActor> originalActor;
  originalActor->GetMapper()->SetInputConnection(source->GetOutputPort());

  vtkNew<vtkImageActor> varianceActor;
  varianceActor->GetMapper()->SetInputConnection(
      varianceCastFilter->GetOutputPort());

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

  // Setup renderers.
  vtkNew<vtkRenderer> originalRenderer;
  originalRenderer->SetViewport(originalViewport);
  originalRenderer->AddActor(originalActor);
  originalRenderer->ResetCamera();
  originalRenderer->SetBackground(.4, .5, .6);
  originalRenderer->SetBackground(
      colors->GetColor3d("CornflowerBlue").GetData());

  vtkNew<vtkRenderer> varianceRenderer;
  varianceRenderer->SetViewport(varianceViewport);
  varianceRenderer->AddActor(varianceActor);
  varianceRenderer->ResetCamera();
  varianceRenderer->SetBackground(colors->GetColor3d("SteelBlue").GetData());

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->SetSize(600, 300);
  renderWindow->AddRenderer(originalRenderer);
  renderWindow->AddRenderer(varianceRenderer);
  renderWindow->SetWindowName("ImageVariance3D");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  vtkNew<vtkInteractorStyleImage> style;

  renderWindowInteractor->SetInteractorStyle(style);

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

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ImageVariance3D)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  ImagingCore
  ImagingGeneral
  ImagingSources
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ImageVariance3D: 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(ImageVariance3D MACOSX_BUNDLE ImageVariance3D.cxx )
  target_link_libraries(ImageVariance3D PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ImageVariance3D
  MODULES ${VTK_LIBRARIES}
)

cd ImageVariance3D/build

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./ImageVariance3D