[vtkusers] Volume Rendering

[Lisa S. Avila]

Hi Massimiliano,

You need to set the scalar type that you are reading. I suspect it defaults 
to unsigned char and you have unsigned short - hence you seem to have two 
copies of the data (the upper 8 bits and the lower 8 bits).

Lisa


At 09:49 AM 10/18/2001, lappadj at libero.it wrote:
>Hi john,
>thank for your help,but i think that the problem is different,i try to
>visualize only one slice with this simple code:
>
>
>#include"vtkImageReader.h"
>#include"vtkImageViewer.h"
>#include"SaveViewerImage.h"
>#include"vtkBMPReader.h"
>
>
>void main(int argc, char*argv[])
>{
>
>
>vtkImageReader *reader = vtkImageReader::New();
>  reader->SetDataByteOrderToLittleEndian();
>  reader->SetDataExtent(0,255,0,255,1,64);
>  reader->SetFilePrefix("c:/vtkdata/patnum/pat");
>  reader->SetDataOrigin(-127.5, -127.5, -32);
>
>
>  reader->SetDataMask(0x7fff);
>  reader->Update();
>
>
>vtkImageViewer *viewer = vtkImageViewer::New();
>  viewer->SetInput(reader->GetOutput());
>  viewer->SetZSlice(3);
>  viewer->SetColorWindow(65536);
>  viewer->SetColorLevel(32768);
>
>viewer->Render();
>
>  SAVEVIEWERIMAGE (viewer);
>
>
>char dummy = '\0';
>  cin >> dummy;
>
>
>reader->Delete();
>viewer->Delete();
>
>}
>and the result is the same:two image in the render window!At this time
>i enclose one image.
>Thanks for any suggestion!
>
>Massimiliano La Paglia
>
>
>
> > Massimiliano,
> >
> > Perhaps if you posted an image of the render window on a website
>somewhere (I
> > don't think you can attach and image to the users group mailing list)
>someone
> > could spot the problem. Its hard to tell what your problem could be
>from the
> > code. You may also want to run your volume read from bmp (imagein)
>through
> > vtkImageLuminance. That helped when I got an ugly render trying to
>work with bmp
> > images...I think I was trying to render the indexed color values
>instead of the
> > intensity. Hope this helps, john
> >
> >
> >
> >  Internet Mail Message
> >  Received from host:      public.kitware.com
> >  [208.136.18.25]
> >
> >
> >
> > From: "lappadj at libero.it" <lappadj at libero.it>@public.kitware.com on
>10/12/2001
> > 10:38 PM ZE2
> >
>
> >                     "lappadj at libero.it"           To:
>"vtkusers"
> >  <lappadj at libero.it>@public.kitware.com
><vtkusers at public.kitware.com>
> >                                                   Cc:    (bcc: John
>Anast-JM/PGI)
> >                                           Subject:      [vtkusers]
>Volume Rendering
> >                                Sent
>by:
> >       vtkusers-
>admin at public.kitware.com
>
> >                     10/12/2001 04:38
>PM
> >
>
> >
>
> >
> >
> >
> >
> > Hi,
> > i utilize this code for rendering one volume of Bmp slices from MRI
> > scan,but the effect of the rendering is not good,the resultant image
> > appear split in two half,is possible to be one error on the slices
> > format,because i convert dicom images into bmp images?Can you help me?
> > Thanks a lot
> >
> > Massimiliano La Paglia
> >
> > #include "vtkRenderer.h"
> > #include "vtkRenderWindow.h"
> > #include "vtkRenderWindowInteractor.h"
> > #include "vtkStructuredPointsReader.h"
> > #include "vtkPiecewiseFunction.h"
> > #include "vtkVolumeProperty.h"
> > #include "vtkVolumeRayCastCompositeFunction.h"
> > #include "vtkVolumeRayCastMapper.h"
> > #include "vtkVolume.h"
> > #include "vtkBMPReader.h"
> >
> > #include "SaveImage.h"
> >
> > void main( int argc, char *argv[] )
> > {
> >   // Create the renderer, render window, and interactor
> >   vtkRenderer *ren1 = vtkRenderer::New();
> >   vtkRenderWindow *renWin = vtkRenderWindow::New();
> >     renWin->AddRenderer(ren1);
> >   vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
> >     iren->SetRenderWindow(renWin);
> >
> >  //Legge bmp file
> >      vtkBMPReader *imagein=vtkBMPReader::New();
> >      imagein->SetFilePrefix ("C:/vtkdata/knee/pat");
> >      imagein->SetDataExtent(0, 255, 0, 255,1,64);
> >
> >
> >      // Create a transfer function mapping scalar value to opacity
> >       vtkPiecewiseFunction *oTFun = vtkPiecewiseFunction::New();
> >       oTFun->AddSegment(80, 0.0, 255, 1.0);
> >
> >   // Create a transfer function mapping scalar value to color (grey)
> >   vtkPiecewiseFunction *cTFun = vtkPiecewiseFunction::New();
> >     cTFun->AddSegment(0, 1.0, 255, 1.0);
> >
> >   // Create a property for the volume and set the transfer functions.
> >   // Turn shading on and use trilinear interpolation
> >   vtkVolumeProperty *volumeProperty = vtkVolumeProperty::New();
> >     volumeProperty->SetColor(cTFun);
> >     volumeProperty->SetScalarOpacity(oTFun);
> >     volumeProperty->SetInterpolationTypeToLinear();
> >     volumeProperty->ShadeOn();
> >
> >   // Create a ray function - this is a compositing ray function
> >   vtkVolumeRayCastCompositeFunction *compositeFunction =
> >     vtkVolumeRayCastCompositeFunction::New();
> >
> >   // Create the volume mapper and set the ray function and scalar
>input
> >   vtkVolumeRayCastMapper *volumeMapper = vtkVolumeRayCastMapper::New
>();
> >     volumeMapper->SetInput(imagein->GetOutput());
> >     volumeMapper->SetVolumeRayCastFunction(compositeFunction);
> >
> >   // Create the volume and set the mapper and property
> >   vtkVolume *volume = vtkVolume::New();
> >     volume->SetMapper(volumeMapper);
> >     volume->SetProperty(volumeProperty);
> >
> >   // Add this volume to the renderer and get a closer look
> >   ren1->AddVolume(volume);
> >   ren1->GetActiveCamera()->Azimuth(20.0);
> >   ren1->GetActiveCamera()->Dolly(1.60);
> >   ren1->ResetCameraClippingRange();
> >
> >   renWin->SetSize(300,300);
> >
> >   renWin->Render();
> >
> >   SAVEIMAGE( renWin );
> >
> >   // Interact with the data at 3 frames per second
> >   iren->SetDesiredUpdateRate(1.0);
> >   iren->SetStillUpdateRate(0.001);
> >   iren->Start();
> >
> >   // Clean up
> >   ren1->Delete();
> >   renWin->Delete();
> >   iren->Delete();
> >   imagein->Delete();
> >   oTFun->Delete();
> >   cTFun->Delete();
> >   volumeProperty->Delete();
> >   compositeFunction->Delete();
> >   volumeMapper->Delete();
> >   volume->Delete();
> > }
> >
> >
> >
> >
> >
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