[Insight-users] Changing the size of the parameters array during registration?

[Luis Ibanez]

Hi Motes

This type of run-time change is done in the Example:

          Insight/Examples/DeformableRegistration15.cxx

Note that the key actions that you have to take care of,
every time that you change the size of the parameters
array are:

1) registration->SetInitialTransformParameters( resizedArray );
2) optimizer->SetScales( resizedOptimizerScales );

That is, the array of optimizer scales must be resized
to the same size of the resized parameters array.

Then, when you call StartRegistration() the metric and
the registration class will initialize their internal arrays
accordingly.



      Regards,


             Luis


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On Fri, Dec 4, 2009 at 4:50 PM, motes motes <mort.motes at gmail.com> wrote:
> I have made a deformable image registration process that after a
> number of iterations pauses the optimizer and based on some criterion
> resizes the parameters array (always to a smaller size).
>
> The the new parameters array is thrown into the image registration
> process and the optimization is continued (the remaining parameters
> are copied to the new parameters array and the optimizer is updated -
> number of optimizer scales).  The jacobian is resized accordingly in
> the transform and so are the number of deformable nodes.
>
> Now I am trying to analyse the effect of resizing the parameters array
> from the optimizer's point of view.  When the optimizer continues to
> work on the new and smaller parameters array (which is initialized
> with the  "surviving" coefficients from the previous parameters array)
> the optimizer search space is actually reduced and the convergence
> should in theory be speed up. But maybe someone has some thought on
> this kind of "dynamic" search space reduction and its consequences?
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