[ITK] [ITK-users] itk Level set function question (old version)

jmerkow jmerkow at gmail.com
Fri Apr 25 00:26:49 EDT 2014


Hello, 
I am working on creating a level set function.  I am looking at the source
code and the reference material and I am a little confused on the
implementation of the level set update function. here the update (phi_t)  =
curvature_term - propagation_term - advection_term - laplacian_term, which
is a rearrangement of the equation in [1].

so, in [1] the curvature term includes 4 variables, gamma, Zed(x), K, and
mag(grad(phi))
in the code (itkLevelSetFunction.hxx), the curvature term is calculated with
3 terms:
curvature_term = this->ComputeCurvatureTerm(it, offset, gd) *
m_CurvatureWeight * this->CurvatureSpeed(it, offset);
Presumably these mappings are
m_CurvatureWeight -> gamma (scalar constant)
Zed(x) -> CurvatureSpeed (spatial modifier)
K -> CurvatureTerm

It would appear that either a term ( mag(grad(phi)) ) is missing (which i
find incredibly hard to believe), or it is grouped into ComputeCurvatureTerm
somehow, but when I follow the references (2d), I arrive at just a curvature
computation (ComputeMeanCurvature).
Whats more, mag(grad(phi)) seems to be explicitly calculated as the
propagation_gradient (later in that same file)

What am I missing?

-Jameson


[1] http://www.itk.org/Doxygen45/html/classitk_1_1LevelSetFunction.html








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