[vtkusers] Filter floaters

[Kevin Osborn]

Thanks for the reply. I'm rendering directly rather than surface 
extracting to try to keep thresholding more interactive. For the same 
reason I was hoping to filter objects after rendering. Looking at the 
island removal filter it seems to be 2D. I will investigate ITK solutions.

Thanks, Kevin



Bill Lorensen wrote:
> Are you directly rendering the data set (Volume Rendering) or
> extracting surfaces? If you are extracting surfaces, have you tried a
> region growing algorithm?
>
> If you are thesholding the data to extract surfaces, you could apply
> vtk's island removal filter. Or, using itk, there are many ways to
> solve the problem, including image morphology, connected component
> labeling, and several region growing techniques.
>
> I suspect that the GE system is using some form of grayscale
> morpohology to filter floaters.
>
> The book "Morphological Image Analysis"
> http://www.amazon.com/Morphological-Image-Analysis-Pierre-Soille/dp/3540429883/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1229890626&sr=8-1
> is outstanding and many of the algorithms described in the book are
> implemented in itk.
>
> Bill
>
> On Sat, Dec 20, 2008 at 6:18 PM, Kevin Osborn <planck at netspeed.com.au> wrote:
>   
>> I am rendering a 3D DICOM data set acquired as 1mm CT slices from a CT
>> angiogram. The images therefore contain a lot of noise which has a similar
>> density value to the tissues of interest. The rendered image contains
>> multiple small separate objects (floaters). I have tried to smooth the
>> images before rendering however that just makes the floaters look smooth
>> :-(. I have used a GE medical workstation in the past that has a function to
>> filter floaters in a rendered image to remove objects below a certain size.
>> I have looked through the VTK class list to try to find a similar filter
>> without luck. Does anyone know of a filter that would do the job?
>>
>> Thanks, Kevin
>>
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>
>