# CurvedReformation

VTKExamples/Cxx/Visualization/CurvedReformation

### Description

This example makes a curved reformation of a volume. The example requires three parameters:

1. Input volume

2. Input polydata that defines a polyline for the reformation. The polyline will be resampled with a cubic spline

3. Resolution is the result resolution of the reformation.

Note

The image was generated with this volume data: HeadMRVolume.mhd and HeadMRVolume.raw](https://github.com/lorensen/VTKExamples/blob/master/src/Testing/Data/HeadMRVolume.raw?raw=true] and this polyLine data:

### Code

CurvedReformation.cxx

    #include <vtkVersion.h>
    #include <vtkSmartPointer.h>

    #include <vtkImageReader2Factory.h>
    #include <vtkImageReader2.h>
    #include <vtkPolyDataReader.h>
    #include <vtkProbeFilter.h>
    #include <vtkImageData.h>
    #include <vtkSplineFilter.h>

    #include <vtkPoints.h>
    #include <vtkCellArray.h>
    #include <vtkPolyData.h>

    #include <vtkWindowLevelLookupTable.h>
    #include <vtkDataSetMapper.h>
    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>

    #include <sstream>

    static vtkSmartPointer<vtkPolyData> SweepLine (vtkPolyData *line,
                                                   double direction[3],
                                                   double distance,
                                                   unsigned int cols);
    int main (int argc, char *argv[])
    {
      // Verify arguments
      if (argc < 4)
      {
          std::cout << "Usage: " << argv[0]
                    << " InputVolume PolyDataInput"
                    << " Resolution"
                    << std::endl;
          return EXIT_FAILURE;
      }

      // Parse arguments
      std::string volumeFileName = argv[1];
      std::string polyDataFileName = argv[2];
      std::stringstream ssResolution;
      ssResolution << argv[3];
      unsigned int resolution;
      ssResolution >> resolution;

      // Output arguments
      std::cout << "InputVolume: " << volumeFileName << std::endl
                << "PolyDataInput: " << polyDataFileName << std::endl
                << "Resolution: " << resolution << std::endl;

      // Read the volume data
      vtkSmartPointer< vtkImageReader2Factory > imageFactory =
        vtkSmartPointer< vtkImageReader2Factory >::New();
      vtkImageReader2 *imageReader =
      imageFactory->CreateImageReader2(volumeFileName.c_str());
      imageReader->SetFileName(volumeFileName.c_str());
      imageReader->Update();

      // Read the Polyline
      vtkSmartPointer<vtkPolyDataReader> polyLineReader =
        vtkSmartPointer<vtkPolyDataReader>::New();
      polyLineReader->SetFileName(polyDataFileName.c_str());
      polyLineReader->Update();

      vtkSmartPointer<vtkSplineFilter> spline =
        vtkSmartPointer<vtkSplineFilter>::New();
      spline->SetInputConnection(polyLineReader->GetOutputPort());
      spline->SetSubdivideToSpecified();
      spline->SetNumberOfSubdivisions(resolution);

      // Sweep the line to form a surface
      double direction[3];
      direction[0] = 0.0;
      direction[1] = 0.0;
      direction[2] = 1.0;
      double distance = 164;
      spline->Update();
      vtkSmartPointer<vtkPolyData> surface =
        SweepLine(spline->GetOutput(),
                  direction,
                  distance,
                  atoi(argv[3]));

      // Probe the volume with the extruded surface
      vtkSmartPointer<vtkProbeFilter> sampleVolume =
        vtkSmartPointer<vtkProbeFilter>::New();
      sampleVolume->SetInputConnection(1, imageReader->GetOutputPort());
    #if VTK_MAJOR_VERSION <= 5
      sampleVolume->SetInput(0, surface);
     #else
      sampleVolume->SetInputData(0, surface);
    #endif
      // Compute a simple window/level based on scalar range
      vtkSmartPointer<vtkWindowLevelLookupTable> wlLut =
        vtkSmartPointer<vtkWindowLevelLookupTable>::New();
      double range = imageReader->GetOutput()->GetScalarRange()[1] -
                     imageReader->GetOutput()->GetScalarRange()[0];
      double level = (imageReader->GetOutput()->GetScalarRange()[1] +
                      imageReader->GetOutput()->GetScalarRange()[0]) / 2.0;
      wlLut->SetWindow(range);
      wlLut->SetLevel(level);

      // Create a mapper and actor.
      vtkSmartPointer<vtkDataSetMapper> mapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapper->SetInputConnection(sampleVolume->GetOutputPort());
      mapper->SetLookupTable(wlLut);
      mapper->SetScalarRange(0, 255);

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

      // Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Add the actors to the scene
      renderer->AddActor(actor);
      renderer->SetBackground(.2, .3, .4);

      // Set the camera for viewing medical images
      renderer->GetActiveCamera()->SetViewUp(0,0,1);
      renderer->GetActiveCamera()->SetPosition(0,0,0);
      renderer->GetActiveCamera()->SetFocalPoint(0,1,0);
      renderer->ResetCamera();

      // Render and interact
      renderWindow->Render();
      renderWindowInteractor->Start();

      imageReader->Delete();
      return EXIT_SUCCESS;
    }

    vtkSmartPointer<vtkPolyData> SweepLine (vtkPolyData *line,
                                            double direction[3],
                                            double distance,
                                            unsigned int cols)
    {
      unsigned int rows = line->GetNumberOfPoints();
      double spacing = distance / cols;
      vtkSmartPointer<vtkPolyData> surface =
        vtkSmartPointer<vtkPolyData>::New();

      // Generate the points
      cols++;
      unsigned int numberOfPoints = rows * cols;
      unsigned int numberOfPolys = (rows - 1) * (cols - 1);
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->Allocate(numberOfPoints);
      vtkSmartPointer<vtkCellArray> polys =
        vtkSmartPointer<vtkCellArray>::New();
      polys->Allocate(numberOfPolys*4);

      double x[3];
      unsigned int cnt = 0;
      for (unsigned int row = 0; row < rows; row++)
      {
          for (unsigned int col = 0; col < cols; col++)
          {
              double p[3];
              line->GetPoint(row, p);
              x[0] = p[0] + direction[0] * col * spacing;
              x[1] = p[1] + direction[1] * col * spacing;
              x[2] = p[2] + direction[2] * col * spacing;
              points->InsertPoint(cnt++, x);
          }
      }
      // Generate the quads
      vtkIdType pts[4];
      for (unsigned int row = 0; row < rows - 1; row++)
      {
          for (unsigned int col = 0; col < cols - 1; col++)
          {
              pts[0] = col + row * (cols);
              pts[1] = pts[0] + 1;
              pts[2] = pts[0] + cols + 1;
              pts[3] = pts[0] + cols;
              polys->InsertNextCell(4,pts);
          }
      }
      surface->SetPoints(points);
      surface->SetPolys(polys);

      return surface;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(CurvedReformation)

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

    add_executable(CurvedReformation MACOSX_BUNDLE CurvedReformation.cxx )

    target_link_libraries(CurvedReformation ${VTK_LIBRARIES})

### Download and Build CurvedReformation

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

    cd CurvedReformation/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:

    ./CurvedReformation

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