[Insight-users] Question for LaplacianSegmentationLevelSetFunction

[Luis Ibanez]

Hi Zhao,

The LaplacianSmoothing weight that you find in the
LevelSetFunction is independent of the Laplacian filter
used at the level of the LaplacianSegmentationLevelSetFunction.

What this last level set function is doing is to apply a
Laplacian filter to the input feature image. Since the
Laplacian filter produces zero crossings at the gradient
maxima of the image, and have negative values in one side,
and positive values in the other side, it results in a very
natural speed image to be used for driving the contour of
the zero-set towards the edges of anatomical structures
present in the input image.

All the computations that are specific to the LaplacianSegmentation
LevelSet filter is done in the  method

             CalculateSpeedImage()

of the LaplacianSegmentationLevelSetFunction class.



   Please let us know if you have further questions


     Thanks



        Luis


-----------------------
zhao yong qiang wrote:

> Hi all,
> 
>   
> 
>          I read the code of this class, and I am puzzled.
> 
> In the base class LevelSetFunction, m_LaplacianSmoothingWeight is set 0. 
> But in the class of LaplacianSegmentationLevelSetFunction, I did not 
> find where this weight was set. So I don’t understand how and where to 
> get the laplacian of the image.
> 
> I think that from LaplacianSegmentationLevelSetFunction,we can get the 
> following PDE,
> 
> dC/dt = Advection term + Curvature term.
> 
> Is it right?
> 
>  
> 
> Regards,
>                           Zhao Yongqiang
>                           Dept. of Computer Science & Engineering
>                           Shanghai JiaoTong University
>                           Shanghai, China
>                           zhao-yq at cs.sjtu.edu.cn 
> <mailto:zhao-yq at cs.sjtu.edu.cn>
> 
>  
> 
> 
> ------------------------------------------------------------------------
> 
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