[vtkusers] How to threshold vtkimage data

[jimcp at cox.net]

Maybe you should contour the air, -1000, there will probably still be some internal structures, nasal passages and etc, but it should be smaller than the tissues with similar scalars to skin. 

---- Ali Habib <ali.mahmoud.habib at gmail.com> wrote: 
> Dear Jim,
> 
> I use this pipline to extract the softtissue only (the human face skin ) but
> internal objects be extracted too , do you any suggestion regarding that
> 
> 
> Best regards
> 
> On Wed, Oct 13, 2010 at 9:43 AM, Jim Peterson <jimcp at cox.net> wrote:
> 
> >  Ali Habib wrote:
> >
> >> Hi All,
> >>  I read a series of DICOM files , and I want to apply threshold (for
> >> further segmentation) but the below cod not effect any more
> >>  vtk.vtkDICOMImageReader VDR = new vtk.vtkDICOMImageReader();
> >>            VDR.SetDirectoryName(@"E:\Master
> >> Degree\DataSet\case2\DICOM\PA1\ST1\SE2");
> >>            VDR.SetDataOrigin(0, 0, 0);
> >>            VDR.Update();
> >>             vtkImageThreshold VIT = new vtkImageThreshold();
> >>          //  VIT.ThresholdBetween(-300, 300);
> >>            VIT.ThresholdByLower(100);
> >>            VIT.SetInputConnection(VDR.GetOutputPort());
> >>                       VIT.Update();
> >>             vtk.vtkImageIslandRemoval2D ImageIslandRemoval2D = new
> >> vtk.vtkImageIslandRemoval2D();
> >>            ImageIslandRemoval2D.SetInput(VIT.GetOutput());
> >>            ImageIslandRemoval2D.SetAreaThreshold(1000);
> >>             vtk.vtkContourFilter skinExtractor = new
> >> vtk.vtkContourFilter();
> >>
> >>  skinExtractor.SetInputConnection(ImageIslandRemoval2D.GetOutputPort());
> >>            //skinExtractor.SetValue(0, 500); // 1123 extract mandible  //
> >>            skinExtractor.GenerateValues(1, -300, 300);
> >>            skinExtractor.ComputeGradientsOn();
> >>  any suggestion pelase
> >>
> > So what were you expecting to have happen and what happened for you? What
> > did you change to cause this to "not effect any more"? Have you been reading
> > the vtk class documentation? See
> > http://www.vtk.org/doc/nightly/html/classvtkContourFilter.html for the
> > contour filter class doc. what are you expecting GenerateValues(1,-300,300)
> > to set as contour values? Does that sound like a appropriate use of that
> > function? how is one output value supposed to include the min and max
> > values?
> >
> > My gut feeling is the island filter with threshold 1000 is removing all
> > features.
> >
> > HTH,
> > Jim
> >
> >