ImageTranslateExtent

VTKEx/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 (http://www.vtk.org/Wiki/VTK/Examples/Cxx/Images/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 simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

ImageTranslateExtent.cxx

#include <vtkImageData.h>
#include <vtkSmartPointer.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>

static void CreateColorImage(vtkImageData* const);

int main(int, char *[])
{
  vtkSmartPointer<vtkImageData> colorImage = vtkSmartPointer<vtkImageData>::New();
  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
//  int extent[6];
//  colorImage->GetExtent(extent);
//  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);

  vtkSmartPointer<vtkImageTranslateExtent> translateExtent =
    vtkSmartPointer<vtkImageTranslateExtent>::New();
  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;

  vtkSmartPointer<vtkSphereSource> sphereSource =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(1.0);
  sphereSource->Update();

  vtkSmartPointer<vtkPolyDataMapper> sphereMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  sphereMapper->SetInputConnection(sphereSource->GetOutputPort());

  vtkSmartPointer<vtkActor> sphereActor =
    vtkSmartPointer<vtkActor>::New();
  sphereActor->SetMapper(sphereMapper);

  vtkSmartPointer<vtkImageSliceMapper> imageSliceMapper = vtkSmartPointer<vtkImageSliceMapper>::New();
  imageSliceMapper->SetInputData(colorImage);

  vtkSmartPointer<vtkImageSlice> imageSlice = vtkSmartPointer<vtkImageSlice>::New();
  imageSlice->SetMapper(imageSliceMapper);
  imageSlice->SetPosition(0,0,0);

  // Setup renderers
  vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
  renderer->AddViewProp(imageSlice);
  renderer->AddViewProp(sphereActor);
  renderer->ResetCamera();

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

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

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

  renderWindowInteractor->SetInteractorStyle(style);

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

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

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

  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] = 255;
      pixel[1] = 0;
      pixel[2] = 255;
    }
  }
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ImageTranslateExtent)

find_package(VTK COMPONENTS 
  vtkvtkCommonCore
  vtkvtkCommonDataModel
  vtkvtkFiltersSources
  vtkvtkImagingCore
  vtkvtkInteractionStyle
  vtkvtkRenderingContextOpenGL2
  vtkvtkRenderingCore
  vtkvtkRenderingFreeType
  vtkvtkRenderingGL2PSOpenGL2
  vtkvtkRenderingOpenGL2 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.