[vtkusers] vtkImageAccumulate

[Ziad Rahhal]

Hi,

Thanx Dean for the help. By Adding input->Update(); to
your suggestion, I was able to see the histogram:

Here is my code:

#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkVolume16Reader.h"
#include "vtkPolyDataMapper.h"
#include "vtkActor.h"
#include "vtkContourFilter.h"

#include "vtkImageAccumulate.h"
#include "vtkXYPlotActor.h"

#include "vtkImageData.h"
#include "vtkImageThreshold.h"

int main (int argc, char **argv)
{
  if (argc < 2)
    {
      cout << "Usage: " << argv[0] <<
"/headsq/quarter" << endl;
      return 1;
    }

  vtkRenderer *aRenderer = vtkRenderer::New();
  vtkRenderWindow *renWin = vtkRenderWindow::New();
    renWin->AddRenderer(aRenderer);
  vtkRenderWindowInteractor *iren =
vtkRenderWindowInteractor::New();
    iren->SetRenderWindow(renWin);

  vtkVolume16Reader *v16 = vtkVolume16Reader::New();
    v16->SetDataDimensions (64,64);
    v16->SetImageRange (1,93);
    v16->SetDataByteOrderToLittleEndian();
    v16->SetFilePrefix (argv[1]);
    v16->SetDataSpacing (3.2, 3.2, 1.5);

  vtkImageData *input = (vtkImageData
*)v16->GetOutput();
    input->Update();
   
  vtkImageAccumulate* accum =
vtkImageAccumulate::New();
    accum->SetInput(input);
    accum->SetComponentSpacing(3.2, 3.2,1.5);
 

  double range[2];
  input->GetScalarRange(range);

  accum->SetComponentExtent(0,
static_cast<int>(range[1] - range[0]), 0, 0, 0, 0);
 
accum->SetComponentOrigin(static_cast<int>(range[0]),
0, 0);
  accum->UpdateWholeExtent();

  vtkXYPlotActor* plot = vtkXYPlotActor::New();
    plot->ExchangeAxesOff();
    plot->SetLabelFormat("%g");
    //plot->SetXRange(accum->GetMin()[0],
accum->GetMax()[0]) ;
    //or
    plot->SetXRange(range[0], range[1]);
    plot->SetYRange(0, 20000);
    plot->SetXTitle("Iso Surface Level");
    plot->SetYTitle("Frequency");
    plot->AddInput(accum->GetOutput());
    plot->SetXValuesToValue();


  aRenderer->AddActor(plot);
 
  renWin->SetSize(640, 480);

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

  v16->Delete();
  accum->Delete();
  plot->Delete();
  iren->Delete();
  renWin->Delete();
  aRenderer->Delete();

  return 0;
}

The problem is that I am supposed to see a peek in
both : iso surface level of 500 and 1150. For the 1150
it is clearly there but why there is no peek at the
500 Value??


Is it a problem of scaling?

I also need to interact with the plot so the user can
pick at a region of the plot and see what does it
visualize (bone or skin) of the head. It should be
like a GUI.

What class should I use that can help me interacting
with the plot? Anybody has a suggestion?

Thank you.

Ziad

--- Dean Inglis <dean.inglis at camris.ca> wrote:

> 
> Here is a pipeline that will do the job:
> 
>   vtkImageAccumulate* accum =
> vtkImageAccumulate::New();
>   accum->SetComponentSpacing(1,0,0);
>   accum->SetInput( input /* your vtkImageData */ );
> 
>   double range[2];
>   input->GetScalarRange( range );
>   accum->SetComponentExtent( 0 ,
> static_cast<int>(range[1]-range[0]), 0, 0,
> 0, 0 );
>   accum->SetComponentOrigin(
> static_cast<int>(range[0]), 0 , 0 );
>   accum->UpdateWholeExtent();
> 
>   vtkXYPlotActor* plot = vtkXYPlotActor::New();
>   plot->ExchangeAxesOff();
>   plot->SetLabelFormat("%g");
>   plot->SetXRange( accum->GetMin()[0],
> accum->GetMax()[0]) ;
>   // or
>   // plot->SetXRange( range) ;
>   plot->AddInput( accum->GetOutput() );
>   plot->SetXValuesToValue();
> 
>   You can do even more interesting things with
> regions of interest
>   if you use a vtkImageStencil in your pipeline.
>   you could also use a vtkImageThreshold on the
> input to look
>   at histogram of soft tissue or hard tissue values
> only.
> 
> Dean
> 
> 
> Hi all,
> 
> I am working with a CT dataset consisting of 93
> slices. Probably you all have this dataset as it is
> included in vtk Examples, it is simply the "headsq".
> 
> I need to make a histogram of the "skin" and "bone"
> pixels to show how many pixels in the dataset
> represent the skin and how many represent the bone.
> 
> I didn't know how to use "vtkImageAccumulate" to
> accomplish this.
> 
> The reader is something like the following:
> 
> vtkVolume16Reader *v16 = vtkVolume16Reader::New();
>     v16->SetDataDimensions (64,64);
>     v16->SetImageRange (1,93);
>     v16->SetDataByteOrderToLittleEndian();
>     v16->SetFilePrefix (argv[1]);
>     v16->SetDataSpacing (3.2, 3.2, 1.5);
> 
> It would be very appreciated if someone can help me
> or
> give me some hints on how to use
> "vtkImageAccumulate"
> with this dataset.
> 
> Thank you
> 
> 
> 
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