[Insight-users] Mean Curvature Calculation in Level Set

[Sah Rayman]

I am now 90% sure that this is a bug of
itkLevelSetFunction.txx as of ITK 1.4.

I rewrote my ComputeMeanCurvature() in my derived
LevelSetFunction class, and the segmentation result
makes more sense. 

My fix:
move line "curvature_term -= gd->m_dx[i] * gd->m_dx[j]
* gd->m_dxy[i][j];"
to the inner of "if( j!=i) ".

Author of the file, if you're interested in more
details, please write to me.



--- Sah Rayman <sahrayman at yahoo . com> wrote:
> I am looking at function:
> 
> template <class TImageType>
> typename
> LevelSetFunction<TImageType>::ScalarValueType
> LevelSetFunction<TImageType>::ComputeMeanCurvature()
> 
> in itkLevelSetFunction.txx, line 158 (ITK 1.4)
> 
> When I compared that to Sethian's "Level Set Methods
> and Fast Marching Methods", 2ndEd, pp. 70, Eq. 6.36,
> I
> found that the C++ implementation contain some extra
> terms in nominator:
> 
> -dx[0]*dx[0]*dxy[0][0]-dx[1]*dx[1]*dxy[1][1]-...
> 
> Can someone tell me what are these additional terms
> for? Is the result still mean curvature? Any
> reference
> for that?
> 
> 
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