[ITK] optimizer scales and weights

[Luigi Riba]

Dear Matt,

thank you very much for the quick reply.

If I've got it correctly the scale parameters tell the optimizer in which
order of magnitude should move in every direction, while the weights are
just used in order to privilege convergence according to a certain number
of sub parameters.

I would rather ask you another question about the scales.  In the
ITK software guide "3.18.2 General heuristics for parameters" it is
suggested to  scale the translation parameters of the optimizer in he
following way
// optimizerScales[9] = 1.0 / (10 * movingSpacing[0] * movingSize[0])
// optimizerScales[10] = 1.0 / (10 * movingSpacing[1] * movingSize[1])
// optimizerScales[11] = 1.0 / (10 * movingSpacing[2] * movingSize[2])

Is this what is done by the SetScaleEstimator() method?

Best,

Luigi



2015-11-09 17:18 GMT+01:00 Matt McCormick <matt.mccormick at kitware.com>:

> Hi Luigi,
>
> The SetScales and SetWeights have different purposes.  SetScales is
> used to account for different parameters having a different impact on
> motion -- for example, translation versus rotation parameters.
> SetWeights can be used to keep one parameter constant, etc.  A more
> detailed description can be found in the class documentation here:
>
>
> http://www.itk.org/Insight/Doxygen/html/classitk_1_1ObjectToObjectOptimizerBaseTemplate.html
>
> HTH,
> Matt
>
> On Mon, Nov 9, 2015 at 10:16 AM, Luigi Riba <ribaluigi at gmail.com> wrote:
> > Dear all,
> >
> > I'm working on ITK 4 and, for the moment, I have always payed attention
> only
> > to the SetScales method for the optimizer.
> >
> > Out of curiosity, what is the role of the SetWeights method? What are the
> > differences between SetWeights and SetScales? Shoud this two methods be
> used
> > in conjunction?
> >
> > Thanks in advance for the help.
> >
> > Best,
> > Luigi
> >
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> >
>
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