[Insight-users] ThresholdSegmentationLevelSet smoothness

[Luis Ibanez]

Hi Oleksandr,

In order to have the curvature weight parameter to have a significant
effect on the level set you have to set it up to a value that is around
100X the one of the propagation weight. These values are relative (they
get normalized inside the filter), so their absolute values do not
matter as much as their relative values. Try pushing it to 200 times
the value of the propagation weight... or even higher.

If you get a rounded sphere as segmentation...
then you will know that you have gone too far :-)


About the first and last slice....
Well, how many empty slices are between the end of the cylinder and
the end of the image ?

You may have to add some padding slices with the PadImageFilter...


   Regards,


     Luis


------------------------
Oleksandr Dzyubak wrote:
> 
> Dear Luis and ITK users,
> 
> I tried to use the ThresholdSegmentationLevelSet image filter
> to segment an elongated gaussian cylinder. The segmentation went fine
> but I still have couple questions.
> 
> 1)
> In the segmented cylinder, its edges are too rough with a bunch of spikes.
> According to the user manual, the CurvatureScaling parameter could be used
> as a smoother but it did not help much even if I vary it over a quite 
> wide range [1-100].
> Any suggestions on how to get the segmented object with smooth edges?
> What other control parameters could be used for that?
> 
> 2)
> In the segmented image, the first and last slices of the cylinder are 
> excluded.
> It looks like propagation gets stuck at the ends.
> Any suggestions on how to enforce it to process the whole object?
> 
> Thanks,
> 
> Alex
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