[Insight-users] FEMRegistration and metrics

[Luis Ibanez]

Hi Francois,


1) The FEM Registration filter does not use
    the ImageMetric classes used in the basic
    Registration Framework. This is due to
    performance and API considerations.

    Therefore the implementaiton of
    NormalizedCorrelation use in FEM is
http://www.itk.org/Insight/Doxygen/html/classitk_1_1NCCRegistrationFunction.html

    and it is independent of the one described in
http://www.itk.org/Insight/Doxygen/html/classitk_1_1NormalizedCorrelationImageToImageMetric.html

    For a list of the metrics availabe for FEM, please
    look at the base class:
http://www.itk.org/Insight/Doxygen/html/classitk_1_1PDEDeformableRegistrationFunction.html




2) About your test with Mutual Information...

    The description of your test is interesting
    but unfortunately lack any technical detail
    that could allow us to help you     :-(

    - We don't know what kind of image modality you are using
    - We don't know if it is 2D, 3D, 4D ...
    - We don't know what parameters you put in your input file

    As you probably undertand, you may have to
    provide more information than just

           "I tried and it didn't work"

    if you expect to get any useful help.



3) For documentation about FEM applied to Image Registration
    you may want to look at the tutorial sessions:

        http://www.itk.org/HTML/Tutorials.htm

    in particular to

http://www.itk.org/CourseWare/Training/NonRigidRegistrationMethods.pdf


    As well as the book

         "Medical Image Registration"
          by Hajnal, Hill and Hawkes

    You can find the book in technical bookstores
    including Amazon.com, and you can also find
    the material online at

       http://www-ipg.umds.ac.uk/d.hill/hhh



4) A chapter on Deformable registration is incluced
    in the book "Insight into Images" that describes
    the theory behind many algorithms in ITK.  The
    book will be available from the editor A.K. Peter
    any day now. This book is also listed in Amazon.com.




Regards,



    Luis




----------------------
Bignalet Francois wrote:

> Hi all!
> 
> I am using the itkFEMRegistrationFilter class and I would have some questions to ask:
> 
> 1) about Normalized Correlation Metric
> 
> It is written in the ITK Software Guide (p283) that itkNormalizedCorrelationImageToImageMetric returns the negative value of the correlation, and so that the optimum is the minimum.
> In the other hand, in the itkFEMRegistrationFilter.h documentation, it is written that the direction associated with ncc is 'maximize'...
> I tried both registration with ncc minimize and ncc maximize, and actually I don't see any big difference. Can anyone help me?
> 
> 2) about MutualInformation
> 
> I tried too to use FEMRegistrationFilter with MI, but I don't manage to have good results. The final output is more different from the fixed image than the moving image input, though I tried maximize and minimize. 
> 
> 3) about Loads and forces
> 
> I read carefuly the Guide and the inline documentation, but I don't really understand how the image loads are converted in forces, how the Jacobian of the metric is used, and how the forces are reconverted in loads after each iteration. Does anyone can tell me about a documentation about FEM applied to images?
> 
> Thanks a lot
> 
> François Bignalet-Cazlet 
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