[Insight-users] DeformableRegistration1

[Luis Ibanez]

Hi Michelangelo,

The cost function being optimized in the FEMRegistrationFilter
is selected in line 33 of the parameter file.

You options are

    Normalized Correlation
    Mean Squares
    Mutual Information

They are implemented in the classes

    itkMeanSquareRegistrationFunction
    itkNCCRegistrationFunction
    itkMIRegistrationFunction


There is no optimization in the case of the FEM registration.

The process is to create "Forces" by using the derivatives
of the local evaluation of the metrics listed above. These
forces are applied to the physical model of the image as
a block of elastic material, and result in a deformation
field. The deformation field is applied to the moving image,
and the forces are computed again, in order to refresh the
deformation field again,... and so on, until convergence.

The FEM framework is rather an energy minimization scheme.


Please keep in mind that the greatest advantage of Open Source
software is that you can see the source code. You may want to
spend some quality time with your favorite text editor going
through the source code of the files:


       Insight/
           Code/
             Algorithms/
                 itkFEMRegistrationFilter.h
                 itkFEMRegistrationFilter.txx




     Regards,


         Luis



========================
Michelangelo Paci wrote:
> Hi,
> I need some explanations about the parameters file used in the 
> DeformableRegistration1 example.
> In particular:
> which kind of interpolator and optimizer is used?
> How the cost function I'm trying to minimize (maximize ? ) is built?
> Thanks
> 
> Michelangelo
> 
> 
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