[Insight-users] geodesic active contours: problems with fast marching

[Sven Prevrhal]

Hi,

I use version 1.2.0 and want to use the geodesic active contours =
application
example for segmenting some bone in a stack of CT images. I use positive
alpha for the sigmoid filter, so the speed image is > 0 inside the bone, =
and
small or zero outside the bone. I place 2 seed points inside the bone on =
the
center slice. I have three difficulties:

1. Seed points and fast marching: The bone splits in two pieces in the =
"top"
slices. How can I avoid having the results of the fast marching leak =
into
the gap between the bone in these slices?

2. The advection term doesn't seem to do anything. I get the same =
results
even for terms > 1.=20

3. The iterations leak into the surrounding tissue almost independently =
of
the slice, ie the result looks the same on all slices.

Help totally appreciated! (Thanks Luis for the last one, the
UpdateLargestPossibleRegion for chaining resampling output to another =
filter
worked!)


:-) sven
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