VTK Iso Slider not working or not showing slider widget

Question

I have some crazy issues in my code, and these issue is:

1) As you see in code below, if I execute it I will got a 3D preview model without sliderWidget. (Fixed)

2) If I change this line from mapper->SetInputConnection(surface->GetOutputPort()); to mapper->SetInputConnection(reader->GetOutputPort()); I will got a sliderWidget but I will not see a 3D model. (Fixed)

3) If I try to set custom key event, its will be work and change value but every change I need to wait until its reload or build 3d dicom (its work like you run and create a 3D model every time not like a slider).

class vtkSliderCallback : public vtkCommand
{
public:
  int counter = 1;
  static vtkSliderCallback *New()
  {
    return new vtkSliderCallback;
  }
  virtual void Execute(vtkObject *caller, unsigned long, void*)
  {
    vtkSliderWidget *sliderWidget =
      reinterpret_cast<vtkSliderWidget*>(caller);
cout << this->counter << endl;
    this->SphereSource->SetValue(this->counter++, static_cast<vtkSliderRepresentation *>(sliderWidget->GetRepresentation())->GetValue());
  }
  vtkSliderCallback():SphereSource(0) {}
  vtkMarchingCubes *SphereSource;
};

int main(int argc, char* argv[])
{
   // Verify input arguments
   if ( argc < 4 )
   {
      std::cout << "Usage: " << argv[0]
      << " DicomSiresFolder" << " isoValueStep" << " OutputDirectory" << std::endl;
      return EXIT_FAILURE;
   }

   std::string folder = argv[1];
  // A sphere

vtkSmartPointer<vtkImageData> volume =
    vtkSmartPointer<vtkImageData>::New();

  vtkSmartPointer<vtkDICOMImageReader> reader =
  vtkSmartPointer<vtkDICOMImageReader>::New();
  reader->SetDirectoryName(folder.c_str());
  reader->Update();

  volume->DeepCopy(reader->GetOutput());

  vtkSmartPointer<vtkMarchingCubes> surface =
        vtkSmartPointer<vtkMarchingCubes>::New();
  surface->SetInputData(volume);
      surface->ComputeNormalsOn();
  surface->SetValue(0, 400);

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

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

  // A renderer and render window
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

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

  // Add the actors to the scene
  renderer->AddActor(actor);

  // Render an image (lights and cameras are created automatically)
  renderWindow->Render();

  vtkSmartPointer<vtkSliderRepresentation3D> sliderRep =
    vtkSmartPointer<vtkSliderRepresentation3D>::New();
  sliderRep->SetMinimumValue(-800.0);
  sliderRep->SetMaximumValue(800.0);
  sliderRep->SetTitleText("Iso Resolution");
  sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToWorld();
  sliderRep->GetPoint1Coordinate()->SetValue(-4,6,0);
  sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToWorld();
  sliderRep->GetPoint2Coordinate()->SetValue(4,6,0);
  sliderRep->SetSliderLength(0.075);
  sliderRep->SetSliderWidth(0.05);
  sliderRep->SetEndCapLength(0.05);

  vtkSmartPointer<vtkSliderWidget> sliderWidget =
    vtkSmartPointer<vtkSliderWidget>::New();
  sliderWidget->SetInteractor(renderWindowInteractor);
  sliderWidget->SetRepresentation(sliderRep);
  sliderWidget->SetAnimationModeToAnimate();
  sliderWidget->EnabledOn();

  vtkSmartPointer<vtkSliderCallback> callback =
    vtkSmartPointer<vtkSliderCallback>::New();
  callback->SphereSource = surface;

  sliderWidget->AddObserver(vtkCommand::InteractionEvent,callback);

  renderWindowInteractor->Initialize();
  renderWindow->Render();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

UPDATE: I Fixed issue on point 1 and 2, but still Issue 3 needed to fix.

Answer 1

Your callback is changing the value for vtkMarchingCube, so you're running a marching cubes every time, so yes, it's rebuilding a mesh every time. As far as I understand what you need to do, one solution can be to precompute vtkMarchingCubes output for all possible values: not elegant (but it could work if you have enough memory). In any case, use vtkFlyingEdges3D instead of vtkMarchingCubes, it's much faster (it could be fast enough to solve your problem without any other modification).