[Insight-users] Changing the speed function

[Luis Ibanez]

Hi Jayant,

You will find useful to read the Chapter
on LevelSets of the SoftwareGuide.

That will solve both of your questions.

You will find the document at:

  http://www.itk.org/ItkSoftwareGuide.pdf

Please read Chapter 9, from pdf-page 363
to 369.

You will find that the speed function can
be changed by providing an input "Feature
Image" and by setting the values of

   - PropagationScaling
   - CurvatureScaling
   - AdvectionScaling

Please, look at the GeodesicActiveContour
in Section 9.3.3, pdf-page 380.

The initial level set must be represented as
an itk::Image<>, as you will find described
in the examples of Chapter 9.

The direction of expansion used for the
speed image can be selected using the method

       ReverseExpansionDirection()

of the SegmentationLevelSetFunction class
http://www.itk.org/Insight/Doxygen/html/classitk_1_1SegmentationLevelSetFunction.html
from which  almost all the LevelSet functions
in ITK derive.



    Regards,


      Luis



---------------------
Jayant Chauhan wrote:
> Hey fellas,
> 2 more questions/doubts, since I am new to ITK,
> 1)  Is there anyway I can decide the speed function I have to use in 
> LEVEL SET METHODs for segmentation, as in, change the propagation, 
> advection and curvature terms ?
>  
> 2) What is the initial level set to be given as (it has to be an 
> itk::Image)? As in, just the boundaries to be high and everything else 
> as low (0) ??! Or inside and outside (inside being high and outside 
> being low)??!!
>   LOW == 0
>   HIGH == 255 ?? So should I just choose the boundary of the image as 
> the initial level set ? Because then I can do that manually pretty 
> easily. Remember, I am using this on the difference image of 2 
> consecutive frames, so I all ready almost the whole of the union of the 
> moving area/object. Will that work ?
>  
>