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ImageTranslateExtent

vtk-examples/Cxx/ImageData/ImageTranslateExtent


Description

If you are looking to change the extent to change the "origin" of the image from the corner to the center, see vtkImageChangeInformation in CenterAnImage.

Currently this method changes the extent (shown by the terminal output in the example), but does not change where the corner of the image is displayed relative to the sphere at (0,0,0).

Question

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

Code

ImageTranslateExtent.cxx

#include <vtkImageData.h>
#include <vtkNew.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkInteractorStyleImage.h>
#include <vtkRenderer.h>
#include <vtkImageMapper.h>
#include <vtkImageSliceMapper.h>
#include <vtkImageSlice.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkImageTranslateExtent.h>
#include <vtkProperty.h>
#include <vtkNamedColors.h>

namespace {
  void CreateColorImage(vtkImageData* const);
}

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

  vtkNew<vtkImageData> colorImage;
  CreateColorImage(colorImage); // This image has (0,0) at the bottom left corner

  int extent[6];
  colorImage->GetExtent(extent);
  std::cout << "Old extent: " << extent[0] << " " << extent[1] << " "
            << extent[2] << " " << extent[3] << " " << extent[4] << " "
            << extent[5] << std::endl;

  // This moves the (0,0) position in the image to the center of the image
  //colorImage->SetExtent(extent[0] - (extent[1] - extent[0]) / 2,
  //                      extent[0] + (extent[1] - extent[0]) / 2,
  //                      extent[2] - (extent[3] - extent[2]) / 2,
  //                      extent[2] + (extent[3] - extent[2]) / 2,
  //                      extent[4] - (extent[5] - extent[4]) / 2,
  //                      extent[4] + (extent[5] - extent[4]) / 2);

  int dimensions[3];
  colorImage->GetDimensions(dimensions);

  vtkNew<vtkImageTranslateExtent> translateExtent;
  translateExtent->SetTranslation(-dimensions[0] / 2, -dimensions[1] / 2, 0);
  translateExtent->SetInputData(colorImage);
  translateExtent->Update();
  colorImage->DeepCopy(translateExtent->GetOutput());

  colorImage->GetExtent(extent);
  std::cout << "New extent: " << extent[0] << " " << extent[1] << " "
            << extent[2] << " " << extent[3] << " " << extent[4] << " "
            << extent[5] << std::endl;

  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(1.0);
  sphereSource->Update();

  vtkNew<vtkPolyDataMapper> sphereMapper;
  sphereMapper->SetInputConnection(sphereSource->GetOutputPort());

  vtkNew<vtkActor> sphereActor;
  sphereActor->SetMapper(sphereMapper);
  sphereActor->GetProperty()->SetColor(colors->GetColor3d("PeachPuff").GetData());

  vtkNew<vtkImageSliceMapper> imageSliceMapper;
  imageSliceMapper->SetInputData(colorImage);

  vtkNew<vtkImageSlice> imageSlice;
  imageSlice->SetMapper(imageSliceMapper);
  imageSlice->SetPosition(0, 0, 0);

  // Setup renderers
  vtkNew<vtkRenderer> renderer;
  renderer->AddViewProp(imageSlice);
  renderer->AddViewProp(sphereActor);
  renderer->ResetCamera();
  renderer->SetBackground(colors->GetColor3d("SteelBlue").GetData());


  // Setup render window
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->SetSize(300, 300);
  renderWindow->AddRenderer(renderer);

  // Setup render window interactor
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;

  vtkNew<vtkInteractorStyleImage> style;

  renderWindowInteractor->SetInteractorStyle(style);

  // Render and start interaction
  renderWindow->SetWindowName("ImageTranslateExtent");

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

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

namespace {

void CreateColorImage(vtkImageData* const image)
{
  image->SetDimensions(10, 10, 1);
  image->AllocateScalars(VTK_UNSIGNED_CHAR, 3);

    vtkNew<vtkNamedColors> colors;
  unsigned char r, g, b, a;
    colors->GetColor("Thistle", r, g, b, a);


  for (unsigned int x = 0; x < 10; x++)
  {
    for (unsigned int y = 0; y < 10; y++)
    {
      unsigned char* pixel =
          static_cast<unsigned char*>(image->GetScalarPointer(x, y, 0));
      pixel[0] = r;
      pixel[1] = g;
      pixel[2] = b;
    }
  }
}

} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ImageTranslateExtent)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersSources
  vtkImagingCore
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping ImageTranslateExtent: ${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(ImageTranslateExtent MACOSX_BUNDLE ImageTranslateExtent.cxx )
  target_link_libraries(ImageTranslateExtent PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(ImageTranslateExtent MACOSX_BUNDLE ImageTranslateExtent.cxx )
  target_link_libraries(ImageTranslateExtent PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS ImageTranslateExtent
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build ImageTranslateExtent

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

cd ImageTranslateExtent/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:

./ImageTranslateExtent

WINDOWS USERS

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