[vtkusers] vtkImageAccumulate using volume too slow

[Michael Knopke]

Hello,

 

I'm looking for a fast way to build a histogram that represents the voxel
distribution in an volume (e.g. 512,512,900).

It's 1 component scalar data (ct slices) represented as unsigned short
(shifted).

 

When using vtkImageAccumulate the following approach works fine when using
2D images (e.g. one slice):

 

    double get_range[2];

    double range;

    mySlice->GetOutput()->GetScalarRange(get_range); // e.g. vtkImageData
with extent (0,511,0,511,0,1);

    range = get_range[1] - get_range[0];    

    int numbins=range/2;

 

    vtkImageAccumulate *histo = vtkImageAccumulate::New();

    histo->SetInput(ResliceInstance->GetOutput());

    //histo->SetInput(SourceObject->GetImageData());

    histo->SetComponentSpacing((get_range[1]/numbins),1,1);

    histo->SetComponentExtent(0,numbins,0,0,0,0);

    histo->SetComponentOrigin(0,0,0);

 

    ... then drawing it vtk vtkImageCanvasSource2D or vtkXYPlotActor (like
in vtkHistogramWidget.tcl)

 

But this represents only the histogram over one slice. However if I use the
whole volume, the histogram is not drawn correctly and computation with
vtkImageAccumulate uses alot of memory and is very slow.

Is there a better way to do this kind of task?

 

Regards

 

Michael

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