[ITK] ImageRegistrationMethodv4 behavior question

[Timothee Evain]

I have stumbled on another curious thing that may be a bug also.
When users set explicitely to not use the sparse sampling with the SetUseFixedSampledPointSet(false) on metric (as shown in the software guide), if the sampling strategy is different of NONE, the option is forcefully set to true when the ImageRegistrationMethodv4 call SetMetricSamplePoints() during the InitializeRegistrationAtEachLevel. This arise when doing first a sparse sampling registration then a dense one.
If sampling strategy is mandatory when we use the sparse sampling, to me it shouldn't impact when using dense sampling.

Tim 




----- Mail original -----
De: "Matt McCormick" <matt.mccormick at kitware.com>
À: "Timothee Evain" <tevain at telecom-paristech.fr>
Cc: community at itk.org
Envoyé: Mercredi 7 Septembre 2016 22:24:22
Objet: Re: [ITK] ImageRegistrationMethodv4 behavior question

Hi Tim,

It sounds like a bug. Do you have patch in mind?

Thanks,
Matt

On Wed, Sep 7, 2016 at 1:05 PM, Timothee Evain
<tevain at telecom-paristech.fr> wrote:
> Hi folks,
>
> It's more a dev consideration, but I've been tricked by the SetNumberOfLevels & SetMetricSamplingPercentage methods from the ImageRegistrationMethodv4.
> The former is overwriting any previously set parameters for SmoothingSigmas and ShrinkFactors but also for the SamplingPercentage.
> If I was expecting it for the two first, as we can only set them per levels via arrays, I was expecting the sampling percentage to be stored since we can set it for all levels via the SetMetricSamplingPercentage method (which in fact is only a wrap around the "per levels" one).
> Thus you cannot set the sampling percentage before setting levels. Is that the intended behavior ? That wasn't really clear to me.
>
> Tim
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