[vtkusers] marching cubes output

[Vetria Byrd]

John,

 

When I changed to volReader->SetDataExtent(04,05,04) nothing is rendered.

I got the iso->SetValue(0,1) from the Medical1, 2 and 3 example code where
the 1 is supposed to correspond to the object.

 

Thanks,

Vetria

 

-----Original Message-----
From: vtkusers-admin at vtk.org [mailto:vtkusers-admin at vtk.org] On Behalf Of
anast.jm at pg.com
Sent: Wednesday, April 07, 2004 3:47 PM
To: vtkusers at vtk.org
Subject: Re: [vtkusers] marching cubes output

 


>From your description, your dataset seems to be 5x6x5 but your coded data
extent is 6x6x6...I'm suprised this didn't generate an error. 

volReader->SetDataExtent(0,5,0,5,0,5); 


also I'm a bit rusty on marching cubes but don't you need a value between 0
and 1 to create the isosurface you are after?? 

iso->SetValue(0,1); 

....john 






 

"Vetria Byrd" <byrdv at cis.uab.edu> 
Sent by: vtkusers-admin at vtk.org 

04/07/2004 04:05 PM 
Please respond to byrdv 

        
        To:        <vtkusers at vtk.org> 
        cc:        (bcc: John Anast-JM/PGI) 
        Subject:        [vtkusers] marching cubes output




I have written a program to extract data from 2D slices of data files. 
Five data files were manually created.  Each of the data files look like
this: 
  
0 0 0 0 0 
0 0 0 0 0 
0 0 1 0 0 
0 0 1 0 0 
0 0 0 0 0 
0 0 0 0 0 
  
Where the 0's indicate the object is outside the cube and 1 indicates the
object is inside the cube. 
When I run the program (which compiles and runs with no problems) I expected
to get a solid object representing the center of the 5x5x5 rendered object
since only the center values of the data (input) show that the object is
inside but what I get is shown in the 1st figure.  Viewing the wire frame
display (2nd figure) shows the 5x5x5 grid with an unexpected dip in the top
row. 
  
I am missing something, I just don't know what that "something" is. 
What I want the algorithm to do is render the object based on which values
of the data indicate the object is present. 
  
Here's the code: 
// 
// This example reads a volume dataset, extracts an isosurface and displays
it. 
// 
  
#include "vtkRenderer.h" 
#include "vtkRenderWindow.h" 
#include "vtkRenderWindowInteractor.h" 
#include "vtkVolumeReader.h" 
#include "vtkImageReader2.h" 
#include "vtkMarchingCubes.h" 
#include "vtkPolyDataMapper.h" 
#include "vtkActor.h" 
#include "vtkOutlineFilter.h" 
#include "vtkCamera.h" 
#include "vtkProperty.h" 
#include "vtkPolyDataNormals.h" 
#include "vtkContourFilter.h" 
  
int main () 
{ 
  
  vtkRenderer *ren = vtkRenderer::New(); 
  vtkRenderWindow *renWin = vtkRenderWindow::New(); 
    renWin->AddRenderer(ren); 
  vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New(); 
    iren->SetRenderWindow(renWin); 
  
  vtkImageReader2 *volReader = vtkImageReader2::New(); 
  volReader->SetDataExtent(0,5,0,5,0,5); 
  volReader->SetFilePrefix("C:/data/cube/slice"); 
  volReader->SetDataSpacing(1,1,1); 
  volReader->Update(); 
  
    
  // An isosurface, or contour value of 1 is known to correspond to the 
  // object 
  vtkMarchingCubes *iso =vtkMarchingCubes::New(); 
     iso->SetInput(volReader->GetOutput() ); 
     iso->SetValue(0,1);   
  
  vtkPolyDataMapper *isoMapper = vtkPolyDataMapper::New(); 
      isoMapper->SetInput(iso->GetOutput() ); 
              
  vtkActor *isoActor = vtkActor::New(); 
      isoActor->SetMapper(isoMapper); 
  
  vtkOutlineFilter *outline = vtkOutlineFilter::New(); 
      outline->SetInput( (vtkDataSet *) volReader->GetOutput() ); 
      
   vtkPolyDataMapper *outlineMapper = vtkPolyDataMapper::New(); 
      outlineMapper->SetInput(outline->GetOutput() ); 
    
   vtkActor *outlineActor = vtkActor::New(); 
      outlineActor->SetMapper(outlineMapper); 
      outlineActor->VisibilityOff(); 
      
   // 
   // Add the actors to the renderer, set the background and size 
   // 
   ren->AddActor(outlineActor); 
   ren->AddActor(isoActor); 
   ren->SetBackground(0.2,0.3,0.4); 
   renWin->SetSize(450,450); 
   ren->GetActiveCamera()->Elevation(90); 
   ren->GetActiveCamera()->SetViewUp(0,0,-1); 
    
   iren->Initialize(); 
    
   // render the image 
   iren->Start(); 
    
  
   return 0; 
} 
  
Thanks. 
_______________ 
Vetria L. Byrd 
  
  

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