[Insight-users] Initial levelset for levelset segmentation

[rahul kumar]

Hi,
i am trying to use levelset for medical data
segmentation. I tried first
thresholdSegmentationlevelset but got one doubt.
For initial level set i ran FastmarchingLevelset which
will result sth like this.

3  2  2  2  2  2  3  3  4  5
2  1  1  1  1  1  2  3  3  4
1  1  0  0  0  1  1  2  3  4
1  0 -1 -1 -1  0  1  1  2  3
0 -1 -2 -2 -2 -1  0  1  2  3
0 -1 -2 -3 -2 -1  0  1  2  3
0 -1 -2 -2 -2 -1  0  1  2  3
1  0 -1 -1 -1  0  1  1  2  3
1  1  0  0  0  1  1  2  3  4
2  1  1  1  1  1  2  3  3  4

but FastMarchingLevelset was taking lots of time so i
created some initiallevelset using sphere
discretization as follows.

4  4  4  4  4  4  4  4  4  4
4  4  4  4  4  4  4  4  4  4
4  4  0  0  0  4  4  4  4  4
4  0 -4 -4 -4  0  4  4  4  4
0 -4 -4 -4 -4 -4  0  4  4  4
0 -1 -4 -4 -4 -4  0  4  4  4
0 -1 -4 -2 -4 -4  0  4  4  4
4  0 -4 -4 -4  0  4  4  4  4
4  4  0  0  0  4  4  4  4  4
4  4  4  4  4  4  4  4  4  4

But the output of Thresholdlevelset is different.  For
later case front is not moving correctly. 
Why it is not working for later case? Afterall front
moves in normal direction  of initial levelset which
is same for both case.

plz enlighten me on this problem.

thnaks a lot.
rahul kumar

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