[vtkusers] isosurface extraction from many bmp files

[Luke Hetrick]

Fellow VTK Users,

    If I could borrow some of your attention for a moment. I am trying to
extract isosurfaces from bmp files. I have written some code that I believe
reads in all my files then go about trying to create a nice smooth surface
but when I render the window and try to view the images, all I see is just
the box holding the data. I assumed if the data types did not work together
an error would have been thrown but that is not the case and when I comment
everything else out except for the code that reads in my files, it stops
and thinks for a bit so I am under the impression that it is reading in my
files. I am just confused as to why the render window comes up blank when I
run the program. Here is the code I am using:

#include <vtkSmartPointer.h>
#include <vtkImageViewer2.h>
#include <vtkBMPReader.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkOutlineFilter.h>
#include <vtkCamera.h>
#include <vtkProperty.h>
#include <vtkPolyDataNormals.h>
#include <vtkContourFilter.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkRenderer.h>

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

  //Read the images
  vtkSmartPointer<vtkBMPReader> bmp =
    vtkSmartPointer<vtkBMPReader>::New();

bmp->SetFilePrefix("../../../../../Auxillary/Data/Data_Set_1/Threshold_Data/fetus_threshold_");

   bmp->SetFilePattern("%s%04d.bmp");
   bmp->SetFileNameSliceOffset(1);
   bmp->SetFileNameSliceSpacing(1);
   bmp->SetNumberOfScalarComponents(3);
   bmp->SetDataSpacing(1,1,1);
   bmp->SetDataOrigin(0,0,0);
   bmp->SetDataExtent(0,400,0,400,22,679);
   bmp->Update();


   //isosurface extraction attempt
   vtkSmartPointer<vtkContourFilter> Extract1 =
     vtkSmartPointer<vtkContourFilter>::New();
   Extract1->SetInputConnection( bmp->GetOutputPort() );
   Extract1->SetValue( 0, 1200 );

   vtkSmartPointer<vtkPolyDataNormals> Normals =
     vtkSmartPointer<vtkPolyDataNormals>::New();
   Normals->SetInputConnection( Extract1->GetOutputPort() );
   Normals->SetFeatureAngle( 60.0 );

   vtkSmartPointer<vtkPolyDataMapper> Mapper =
     vtkSmartPointer<vtkPolyDataMapper>::New();
   Mapper->SetInputConnection( Normals->GetOutputPort() );
   Mapper->ScalarVisibilityOff();

   vtkSmartPointer<vtkActor> Actor =
     vtkSmartPointer<vtkActor>::New();
   Actor->SetMapper( Mapper );

  // An outline provides context around the data.
  vtkSmartPointer<vtkOutlineFilter> outlineData =
    vtkSmartPointer<vtkOutlineFilter>::New();
  outlineData->SetInputConnection( bmp->GetOutputPort() );

  vtkSmartPointer<vtkPolyDataMapper> mapOutline =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapOutline->SetInputConnection( outlineData->GetOutputPort() );

  vtkSmartPointer<vtkActor> outline =
    vtkSmartPointer<vtkActor>::New();
  outline->SetMapper( mapOutline );
  outline->GetProperty()->SetColor( 0,0,0 );

  // It is convenient to create an initial view of the data. The FocalPoint
  // and Position form a vector direction. Later on (ResetCamera() method)
  // this vector is used to position the camera to look at the data in
  // this direction.
  vtkSmartPointer<vtkCamera> aCamera =
    vtkSmartPointer<vtkCamera>::New();
  aCamera->SetViewUp ( 0, 0, -1 );
  aCamera->SetPosition ( 0, 1, 0 );
  aCamera->SetFocalPoint ( 0, 0, 0 );
  aCamera->ComputeViewPlaneNormal();
  aCamera->Azimuth( 30.0 );
  aCamera->Elevation( 30.0 );

  // Create the renderer, the render window, and the interactor. The
renderer
  // draws into the render window, the interactor enables mouse and
  // keyboard-based interaction with the data within the render window.
  vtkSmartPointer<vtkRenderer> aRenderer =
    vtkSmartPointer<vtkRenderer>::New();

  vtkSmartPointer<vtkRenderWindow> renWin =
    vtkSmartPointer<vtkRenderWindow>::New();
  renWin->AddRenderer(aRenderer);

  vtkSmartPointer<vtkRenderWindowInteractor> iren =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  iren->SetRenderWindow(renWin);

  vtkSmartPointer<vtkInteractorStyleTrackballCamera> Style =
    vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();

  // Actors are added to the renderer. An initial camera view is created.
  // The Dolly() method moves the camera towards the FocalPoint,
  // thereby enlarging the image.
  aRenderer->AddActor( outline );
  aRenderer->AddActor( Actor );
  aRenderer->SetActiveCamera( aCamera );
  aRenderer->ResetCamera();
  aCamera->Dolly( 1.5 );

  // Set a background color for the renderer and set the size of the
  // render window (expressed in pixels).
  aRenderer->SetBackground( .2, .3, .4 );
  renWin->SetSize( 640, 480 );

  // Note that when camera movement occurs (as it does in the Dolly()
  // method), the clipping planes often need adjusting. Clipping planes
  // consist of two planes: near and far along the view direction. The
  // near plane clips out objects in front of the plane; the far plane
  // clips out objects behind the plane. This way only what is drawn
  // between the planes is actually rendered.
  aRenderer->ResetCameraClippingRange();

  // Initialize the event loop and then start it.
  iren->SetInteractorStyle( Style );
  iren->Initialize();
  iren->Start();



  return EXIT_SUCCESS;
}

There are a few parameters that I can adjust that would have a large impact
on the surface I am trying to extract that may be the reason why I am not
seeing a volume. SOme of the parapmeters Ithink would be a problem would be
the many properites of bmp and the Normals->SetAngle() property. If you
have had similar experience to this or just have an idea of why I can not
view anything in the render window, please let me know your thoughts.

Thanks,
Luke H
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