ImageDivergence

VTKExamples/Cxx/Images/ImageDivergence


Code

ImageDivergence.cxx

#include <vtkSmartPointer.h>
#include <vtkImageCast.h>
#include <vtkImageData.h>
#include <vtkImageMapper3D.h>
#include <vtkImageCanvasSource2D.h>
#include <vtkImageDivergence.h>
#include <vtkImageGradient.h>
#include <vtkImageCanvasSource2D.h>
#include <vtkImageCorrelation.h>
#include <vtkInteractorStyleImage.h>
#include <vtkImageActor.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkImageMandelbrotSource.h>

int main(int, char *[])
{
  // Create an image
  vtkSmartPointer<vtkImageMandelbrotSource> source =
    vtkSmartPointer<vtkImageMandelbrotSource>::New();
  source->Update();

  vtkSmartPointer<vtkImageCast> originalCastFilter =
    vtkSmartPointer<vtkImageCast>::New();
  originalCastFilter->SetInputConnection(source->GetOutputPort());
  originalCastFilter->SetOutputScalarTypeToFloat();
  originalCastFilter->Update();

  // Compute the gradient (to produce a vector field)
  vtkSmartPointer<vtkImageGradient> gradientFilter =
    vtkSmartPointer<vtkImageGradient>::New();
  gradientFilter->SetInputConnection(source->GetOutputPort());
  gradientFilter->Update();

  vtkSmartPointer<vtkImageDivergence> divergenceFilter = 
    vtkSmartPointer<vtkImageDivergence>::New();
  divergenceFilter->SetInputConnection(gradientFilter->GetOutputPort());
  divergenceFilter->Update();

  vtkSmartPointer<vtkImageCast> divergenceCastFilter =
    vtkSmartPointer<vtkImageCast>::New();
  divergenceCastFilter->SetInputConnection(divergenceFilter->GetOutputPort());
  divergenceCastFilter->SetOutputScalarTypeToFloat();
  divergenceCastFilter->Update();

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

  vtkSmartPointer<vtkImageActor> divergenceActor =
    vtkSmartPointer<vtkImageActor>::New();
  divergenceActor->GetMapper()->SetInputConnection(
    divergenceCastFilter->GetOutputPort());

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

  // Setup renderers
  vtkSmartPointer<vtkRenderer> originalRenderer =
    vtkSmartPointer<vtkRenderer>::New();
  originalRenderer->SetViewport(leftViewport);
  originalRenderer->AddActor(originalActor);
  originalRenderer->ResetCamera();

  vtkSmartPointer<vtkRenderer> divergenceRenderer =
    vtkSmartPointer<vtkRenderer>::New();
  divergenceRenderer->SetViewport(rightViewport);
  divergenceRenderer->AddActor(divergenceActor);
  divergenceRenderer->ResetCamera();

  // Setup render window
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->SetSize(600,300);
  renderWindow->AddRenderer(originalRenderer);
  renderWindow->AddRenderer(divergenceRenderer);

  // Setup render window interactor
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  vtkSmartPointer<vtkInteractorStyleImage> style =
    vtkSmartPointer<vtkInteractorStyleImage>::New();

  renderWindowInteractor->SetInteractorStyle(style);

  // Render and start interaction
  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderWindow->Render();
  renderWindowInteractor->Initialize();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ImageDivergence)

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

Download and Build ImageDivergence

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

cd ImageDivergence/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:

./ImageDivergence

WINDOWS USERS

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