# RenderLargeImage

VTKExamples/Cxx/Visualization/RenderLargeImage

### Description

This example renders a high resolution image. The image can be much larger than the window on the screen. It is useful if you need an image for a large poster, or you can down sample the image to produce a high quality anti-aliased image.

The example takes up to three arguments. The first, an input polydata, is required, as is the second, a .png file to hold the high res image. An optional third argument specifies the magnification of the high res image (default 4).

### Code

RenderLargeImage.cxx

    #include <vtkSmartPointer.h>

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkImageViewer.h>
    #include <vtkPNGWriter.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkRenderLargeImage.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkXMLPolyDataReader.h>

    int main (int argc, char *argv[])
    {
      if (argc < 3)
      {
        std::cerr << "Usage: " << argv[0]
                  << " Input(.vtp) Output(.png) [Magnification]"
                  << std::endl;
        return EXIT_FAILURE;
      }
      int magnification = 4;
      if (argc == 4)
      {
        magnification = atoi(argv[3]);
      }

      vtkSmartPointer<vtkXMLPolyDataReader> reader =
        vtkSmartPointer<vtkXMLPolyDataReader>::New();
      reader->SetFileName(argv[1]);

      vtkSmartPointer<  vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(reader->GetOutputPort());

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();

      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);

      renderWindow->AddRenderer(renderer);

      renderer->AddActor(actor);

      // Let the renderer compute good position and focal point
      renderer->GetActiveCamera()->Azimuth(30);
      renderer->GetActiveCamera()->Elevation(30);
      renderer->ResetCamera();
      renderer->GetActiveCamera()->Dolly(1.4);
      renderer->ResetCameraClippingRange();
      renderer->SetBackground(.3, .4, .5);

      renderWindow->SetSize(640, 480);
      renderWindow->Render();

      std::cout << "Interact with image to get desired view and then press 'e'"
                << std::endl;
      interactor->Start();
      std::cout << "Generating large image size: "
                << renderWindow->GetSize()[0] * magnification << " by "
                << renderWindow->GetSize()[1] * magnification
                << std::endl;

      vtkSmartPointer<vtkRenderLargeImage> renderLarge =
        vtkSmartPointer<vtkRenderLargeImage>::New();
      renderLarge->SetInput(renderer);
      renderLarge->SetMagnification(magnification);

      std::cout << "Saving image in " << argv[2] << std::endl;
      vtkSmartPointer<vtkPNGWriter> writer =
        vtkSmartPointer<vtkPNGWriter>::New();
      writer->SetFileName(argv[2]);
      writer->SetInputConnection(renderLarge->GetOutputPort());
      writer->Write();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(RenderLargeImage)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(RenderLargeImage MACOSX_BUNDLE RenderLargeImage.cxx )

    target_link_libraries(RenderLargeImage ${VTK_LIBRARIES})

### Download and Build RenderLargeImage

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

    cd RenderLargeImage/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:

    ./RenderLargeImage

WINDOWS USERS

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