[vtkusers] vtkDiscreteMarchingCubes extend

[Cagatay Bilgin]

Hi Bill,

#include "itkImageToVTKImageFilter.h"
#include "itkVTKImageToImageFilter.h"

#include <vtkDiscreteMarchingCubes.h>
#include <vtkSmartPointer.h>

#include  "itkImageFileWriter.h"
#include  "itkImageFileReader.h"


#include "vtkPolyDataMapper.h"
#include "vtkActor.h"
#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"

int main(int argc, char*argv[]){

  if(argc!=2){
    std::cout << argv[0] << " inputFileName.mhd" << std::endl;
    return -1;
  }

  typedef itk::Image<unsigned int,3> ImageType;
  typedef itk::ImageFileReader<ImageType> ReaderType;
  ReaderType::Pointer reader = ReaderType::New();
  reader->SetFileName(argv[1]);
  reader->Update();
  ImageType::Pointer input = reader->GetOutput();

  typedef itk::ImageToVTKImageFilter<ImageType> ITK2VTKType;
  ITK2VTKType::Pointer itk2vtk = ITK2VTKType::New();
  itk2vtk->SetInput(input);
  itk2vtk->Update();

  //extent and origin seems correct
  double* origin  = itk2vtk->GetOutput()->GetOrigin();
  int* extent  = itk2vtk->GetOutput()->GetExtent();
  std::cout << input->GetLargestPossibleRegion().GetIndex() << std::endl;
  std::cout << extent[0] << " " << extent[1] << " "
            << extent[2] << " " << extent[3] << " "
            << extent[4] << " " << extent[5] << std::endl;

  vtkSmartPointer<vtkDiscreteMarchingCubes> discreteCubes =
    vtkSmartPointer<vtkDiscreteMarchingCubes>::New();
  discreteCubes->SetInput(itk2vtk->GetOutput());
  discreteCubes->GenerateValues(1, 1, 1); //TODO Fixed numbers
  discreteCubes->Update();

  //The object starts around the 10th slice, there is a problem here.
  vtkSmartPointer<vtkPolyData> cubes = discreteCubes->GetOutput();
  for(unsigned int i = 0; i < cubes->GetNumberOfPoints(); i++)
  {
    double p[3];
    cubes->GetPoint(i, p);
    std::cout << p[0] << " " << p[1] << " " << p[2] << std::endl;
  }


  // Create a mapper and actor
  vtkSmartPointer<vtkPolyDataMapper> surfaceMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  surfaceMapper->SetInputConnection(discreteCubes->GetOutputPort());
  vtkSmartPointer<vtkActor> surfaceActor = vtkSmartPointer<vtkActor>::New();
  surfaceActor->SetMapper(surfaceMapper);

  // 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 actor to the scene
  renderer->AddActor(surfaceActor);
  renderer->SetBackground(.1, .2, .3); // Background color blue
  renderWindow->Render();
  renderWindowInteractor->Start();

}

I have also uploaded the data I am using here:
http://vision.lbl.gov/People/bilgin/input.tar.gz

All I am trying to do is obtain the indices of points on the
surface.

Thank you,
Cagatay

On Mon, May 7, 2012 at 12:46 PM, Bill Lorensen <bill.lorensen at gmail.com>wrote:

> Please post a small compilable example that illustrates the problem.
>
> On Mon, May 7, 2012 at 2:18 PM, Cagatay Bilgin <bilgincc at gmail.com> wrote:
> > Hello vtk-users
> >
> > I am having problems understanding the
> > output of vtkDiscreteMarchingCubes.
> >
> > when I print the output polydata points, they
> > do not match the input positions. It looks like
> > the filter is doing a bounding box for the
> > object. The extent and the origin seems
> > to change. My sphere is located around 100,100,100
> > with a radius of 10 in the input image, after the
> > marching cubes it is around 10,10,10 with a
> > radius of 10. How can make the filter give me
> > the correct indices ?
> >
> > Thanks,
> > Cagatay
> >
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> --
> Unpaid intern in BillsBasement at noware dot com
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