[vtkusers] VTKpolydata (2D polygon) to VTKimagedata

[Neda]

Dear all,

I searched a lot in the google but I could not solve my problem. I hope some
one helps me here. 
 
what I want to do is creating the corresponding binary image of a polygon
(vtkPolydata) in a 2D image.
To do this I found a function called "vtkPolyDataToImageStencil" but it
gives me a totally black image.
I do not know what is wrong in my code (I attached my code here)

I will appreciate if some one tells me how can I solve this problem.
Did I choose a correct function to do this?

Regards,
Neda
/**************************************************************************************************************
#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkImageData.h>
#include <vtkSphereSource.h>
#include <vtkMetaImageWriter.h>
#include <vtkPolyDataToImageStencil.h>
#include <vtkImageStencil.h>
#include <vtkPointData.h>
#include <vtkCutter.h>
#include <vtkPlane.h>
#include <vtkStripper.h>
#include <vtkLinearExtrusionFilter.h>
#include <vtkXMLPolyDataWriter.h>
 #include <vtkPolygon.h>
#include <vtkCellArray.h>

int main(int, char *[])
{

      // Setup four points
      vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(10.0, 10.0, 0.0);
      points->InsertNextPoint(10.0, 50.0, 0.0);
      points->InsertNextPoint(30.0, 10.0, 0.0);
      points->InsertNextPoint(30.0, 20.0, 0.0);

      // Create the polygon
      vtkSmartPointer<vtkPolygon> polygon =
vtkSmartPointer<vtkPolygon>::New();
      polygon->GetPointIds()->SetNumberOfIds(4); //make a quad
      polygon->GetPointIds()->SetId(0, 0);
      polygon->GetPointIds()->SetId(1, 1);
      polygon->GetPointIds()->SetId(2, 2);
      polygon->GetPointIds()->SetId(3, 3);

      // Add the polygon to a list of polygons
      vtkSmartPointer<vtkCellArray> polygons =
vtkSmartPointer<vtkCellArray>::New();
      polygons->InsertNextCell(polygon);

      // Create a PolyData
      vtkSmartPointer<vtkPolyData> polygonPolyData
=vtkSmartPointer<vtkPolyData>::New();
      polygonPolyData->SetPoints(points);
      polygonPolyData->SetPolys(polygons);


  vtkSmartPointer<vtkStripper> stripper =
vtkSmartPointer<vtkStripper>::New();
  stripper->SetInput(polygonPolyData); // valid circle
  stripper->Update();
  vtkSmartPointer<vtkPolyData> circle = stripper->GetOutput();

  // prepare the binary image's voxel grid
  vtkSmartPointer<vtkImageData> whiteImage = 
vtkSmartPointer<vtkImageData>::New();
  double bounds[6];
  circle->GetBounds(bounds);
  double spacing[3]; // desired volume spacing
  spacing[0] = 0.67;
  spacing[1] = 0.67;
  spacing[2] = 5;
  whiteImage->SetSpacing(spacing);

  // compute dimensions
  int dim[3];
  dim[0]=512;
  dim[1]=512;
  dim[2]=1;

  whiteImage->SetDimensions(dim);
  whiteImage->SetExtent(0, dim[0] - 1, 0, dim[1] - 1, 0, dim[2] - 1);
  double origin[3];
  // NOTE: I am not sure whether or not we had to add some offset!
  origin[0] = bounds[0];
  origin[1] = bounds[2];
  origin[2] = bounds[4];
  whiteImage->SetOrigin(origin);

  whiteImage->SetScalarTypeToUnsignedChar();
  whiteImage->AllocateScalars();

  // fill the image with foreground voxels:
  unsigned char inval = 255;
  unsigned char outval = 0;
  vtkIdType count = whiteImage->GetNumberOfPoints();
  for (vtkIdType i = 0; i < count; ++i)
    {
    whiteImage->GetPointData()->GetScalars()->SetTuple1(i, inval);
    }

  // sweep polygonal data (this is the important thing with contours!)
  vtkSmartPointer<vtkLinearExtrusionFilter> extruder =
vtkSmartPointer<vtkLinearExtrusionFilter>::New();
  extruder->SetInput(circle);
  extruder->SetScaleFactor(1.);
  extruder->SetExtrusionTypeToNormalExtrusion();
  extruder->SetVector(0, 0, 1);
  extruder->Update();

  // polygonal data --> image stencil:
  vtkSmartPointer<vtkPolyDataToImageStencil> pol2stenc =
vtkSmartPointer<vtkPolyDataToImageStencil>::New();
  pol2stenc->SetTolerance(0); // important if extruder->SetVector(0, 0, 1)
!!!
  pol2stenc->SetInputConnection(extruder->GetOutputPort());
  pol2stenc->SetOutputOrigin(origin);
  pol2stenc->SetOutputSpacing(spacing);
  pol2stenc->SetOutputWholeExtent(whiteImage->GetExtent());
  pol2stenc->Update();

  // cut the corresponding white image and set the background:
  vtkSmartPointer<vtkImageStencil> imgstenc
=vtkSmartPointer<vtkImageStencil>::New();
  imgstenc->SetInput(whiteImage);
  imgstenc->SetStencil(pol2stenc->GetOutput());
  imgstenc->ReverseStencilOff();
  imgstenc->SetBackgroundValue(outval);
  imgstenc->Update();

  vtkSmartPointer<vtkMetaImageWriter> imageWriter =
vtkSmartPointer<vtkMetaImageWriter>::New();
  imageWriter->SetFileName("labelImage.mhd");
  imageWriter->SetInputConnection(imgstenc->GetOutputPort());
  imageWriter->Write();

  imageWriter->SetFileName("whiteimage.mhd");
  imageWriter->SetInput(whiteImage);
  imageWriter->Write();

  return EXIT_SUCCESS;
}



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