[vtkusers] vtkPolyDataToImageStencil noise issue

[Raghuram.O.S.]

On Mon, Mar 19, 2012 at 7:35 AM, Jothybasu Selvaraj <jothybasu at gmail.com>wrote:

> What is your polydata made of?
>
> Is it from 2D contours?
>

My polydata has 3D triangles. Here is the DumpXML output for it.
------------------------
out_p_w.vtk
 contains a
vtkPolyData that has 1310888 cells and 1772275 points.
Cell type vtkTriangle occurs 1310888 times.
 contains point data with 2 arrays.
Array 0 is named scalars
Array 1 is named Normals
 contains cell data with 0 arrays.
 contains field data with 0 arrays.



>
> You may post your code, that would make people to help you better.
>

Sorry, I should have done that.

int main(int, char *[])
{
    vtkSmartPointer<vtkPolyDataReader> pdR =
        vtkSmartPointer<vtkPolyDataReader>::New();
  vtkSmartPointer<vtkSphereSource> sphereSource =
    vtkSmartPointer<vtkSphereSource>::New();
  vtkSmartPointer<vtkWarpScalar> warp=
    vtkSmartPointer<vtkWarpScalar>::New();
  sphereSource->SetRadius(20);
  sphereSource->SetPhiResolution(30);
  sphereSource->SetThetaResolution(30);
  pdR->SetFileName("../../data/vtk/out_p_w.vtk");
  //pdR->SetFileName("../../data/vtk/out_poly_append_one.vtk");
  //pdR->SetFileName("../../vis/out_poly.vtk");
  //vtkSmartPointer<vtkPolyData> pd = sphereSource->GetOutput();
  pdR->Update();
  vtkSmartPointer<vtkPolyData> pd = pdR->GetOutput();
  //warp->SetInput(pd);
  //warp->SetScaleFactor(10);
  //warp->Update();
  //vtkSmartPointer<vtkPolyData> pd =
  //pd = warp->GetOutput();
  //sphereSource->Update();

  vtkSmartPointer<vtkImageData> whiteImage =
    vtkSmartPointer<vtkImageData>::New();
  double bounds[6];
  pd->GetBounds(bounds);
  double spacing[3]; // desired volume spacing
  spacing[0] = 0.31;
  spacing[1] = 0.31;
  spacing[2] = 0.31;
  whiteImage->SetSpacing(spacing);

  // compute dimensions
  int dim[3];
  for (int i = 0; i < 3; i++)
    {
    dim[i] = static_cast<int>(ceil((bounds[i * 2 + 1] - bounds[i * 2]) /
spacing[i]));
    }
  whiteImage->SetDimensions(dim);
  whiteImage->SetExtent(0, dim[0] - 1, 0, dim[1] - 1, 0, dim[2] - 1);

  double origin[3];
  origin[0] = bounds[0] + spacing[0] / 2;
  origin[1] = bounds[2] + spacing[1] / 2;
  origin[2] = bounds[4] + spacing[2] / 2;
  whiteImage->SetOrigin(origin);

#if VTK_MAJOR_VERSION <= 5
  whiteImage->SetScalarTypeToUnsignedChar();
  whiteImage->AllocateScalars();
#else
  whiteImage->AllocateScalars(VTK_UNSIGNED_SHORT,1);
#endif
  // 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);
    }

  // polygonal data --> image stencil:
  vtkSmartPointer<vtkPolyDataToImageStencil> pol2stenc =
    vtkSmartPointer<vtkPolyDataToImageStencil>::New();
#if VTK_MAJOR_VERSION <= 5
  pol2stenc->SetInput(pd);
#else
  pol2stenc->SetInputData(pd);
#endif
  pol2stenc->SetOutputOrigin(origin);
  pol2stenc->SetOutputSpacing(spacing);
  pol2stenc->SetOutputWholeExtent(whiteImage->GetExtent());
  pol2stenc->Update();

  vtkSmartPointer<vtkImplicitFunctionToImageStencil> func2stenc =
  vtkImplicitFunctionToImageStencil::New();
  //vtkSmartPointer<vtkElevationFilter> elev = vtkElevationFilter::New();
  //elev->SetInput(pd);
  //vtkSmartPointer<vtkImplicitDataSet> imp = vtkImplicitDataSet::New();
  //imp->SetDataSet(elev->GetOutput());

  //func2stenc->SetThreshold(0.1);
  //func2stenc->SetInput(imp);
  //func2stenc->SetOutputOrigin(origin);
  //func2stenc->SetOutputSpacing(spacing);
  //func2stenc->SetOutputWholeExtent(whiteImage->GetExtent());
  //func2stenc->Update();

  // cut the corresponding white image and set the background:
  vtkSmartPointer<vtkImageStencil> imgstenc =
    vtkSmartPointer<vtkImageStencil>::New();
#if VTK_MAJOR_VERSION <= 5
  imgstenc->SetInput(whiteImage);
  imgstenc->SetStencil(pol2stenc->GetOutput());
  //imgstenc->SetStencil(func2stenc->GetOutput());
#else
  imgstenc->SetInputData(whiteImage);
  imgstenc->SetStencilConnection(pol2stenc->GetOutputPort());
  //imgstenc->SetStencilConnection(func2stenc->GetOutputPort());
#endif
  //imgstenc->ReverseStencilOff();
  imgstenc->SetBackgroundValue(outval);
  imgstenc->Update();

  vtkSmartPointer<vtkMetaImageWriter> writer =
    vtkSmartPointer<vtkMetaImageWriter>::New();
  writer->SetFileName("SphereVolume_p_w.mhd");
#if VTK_MAJOR_VERSION <= 5
  writer->SetInput(imgstenc->GetOutput());
#else
  writer->SetInputData(imgstenc->GetOutput());
#endif
  writer->Write();

  return EXIT_SUCCESS;
}





>
> Jothy
>
> On Mon, Mar 19, 2012 at 2:51 AM, Raghuram.O.S. <raghuramos1987 at gmail.com>wrote:
>
>> Hi,
>>
>> I have been trying to convert polydata to imagedata using the image
>> stencil filter. I seem to be running into an issue of noise in the
>> converted image. I get random triangles in the image which are pretty huge
>> in the middle of actual data. I saw this post
>> http://www.vtk.org/pipermail/vtkusers/2011-October/119302.html and tried
>> using the implicit function. But, the post doesnt have a full example and
>> there doesnt seem to be an example of vtkImplicitFunctionToImageStencil.
>>
>> My polydata doesnt seem to have any issues when I render it using
>> polydatamapper. I have been using the example on the site at
>> http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataToImageData (as
>> indicated in the previous post also).
>> --
>> Regards,
>> Onti
>>
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>
>
> --
> Jothy
>
>


-- 
Regards,
Onti
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