[Insight-users] about level set methods

[Burak Özkalaycı]

 Dear all,

I am a little bit confused about the level set implementation in ITK.
my questions are according to

http://www.itk.org/Doxygen32/html/itkLevelSetFunction_8h.html and
http://www.itk.org/Doxygen32/html/itkSegmentationLevelSetFunction_8h.html

There exist m_FeatureImage, m_SpeedImage, m_AdvectionImage,
PropagationSpeed, CurvatureSpeed. The levelset function to be solved is
given as :

http://www.itk.org/Doxygen32/html/form_149.png

I think
m_AdvectionImage = A(x);
PropagationSpeed = P(x);
CurvatureSpeed = Z(x);

1- According to my understand the m_SpeedImage is expected to be calculated
from the m_FeatureImage in a desired fashion. that's why it is not
implemented. However I can not find the connection of this m_SpeedImage with
the A, P, Z terms?
2- How Z is calculated, I could not find anything about it also?
3- According to Osher's  Level Set Methods book the right hand side of the
equation
http://www.itk.org/Doxygen32/html/form_149.png
should be calculated by using center differences. Is it implemented like
that?
4- Are the magnitude of the gradients of Phi same for the right and left
side of that equation? (since the left side should use the upwind methods
where the right side should use center differences)

If anyone can answer my implementation and theory based questions I will be
so glad. And also any reference to headers or sources are welcome.

Thank you in advance

Burak



  Burak Ozkalayci <burak.ozkalayci at UGent.be>  PhD Student  Electronic and
Information Systems (ELIS-MEDISIP)  Ghent University Hospital - IBITECH
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