[Insight-developers] Multi-resolution pyramid and multi-resolution PDE deformable registration small issues

[Tom Vercauteren]

Thanks for the feedback.

Stephen: Just like Gaetan, I don't really the option of having a wrong
default behavior. I consider the over-smoothing and inconsistency
between MultiResolutionPyramidImageFilter and
RecursiveMultiResolutionPyramidImageFilter to be a bug. Therefore,
correcting it shouldn't be seen as breaking backwards compatibility.
But of course that's my point of view.

Also, since it is possible for the user to change the multi-resolution
pyramid in MultiResolutionPDEDeformableRegistration, I don't gain much
if the default bebahior of MultiResolutionPyramidImageFilter stays the
same. I'd rather not modify ITK and tweak the multi-resolution pyramid
in MultiResolutionPDEDeformableRegistration from my application.


Hans: I have looked at the patch you mention:
http://public.kitware.com/cgi-bin/viewcvs.cgi/Code/Algorithms/itkMultiResolutionPyramidImageFilter.txx?root=Insight&r1=1.29&r2=1.25

Is there any reason why the smoother changed from
  smoother->SetUseImageSpacing( false );
to
  smoother->SetUseImageSpacing( true );

It seems like "smoother->SetUseImageSpacing( false );" should be the
right version to use as the sigma is computed only from the pyramid
schedule.

Apart from that fixing this in
RecursiveMultiResolutionPyramidImageFilter shouldn't be a problem.

Tom

On Thu, Mar 5, 2009 at 15:06, Hans Johnson <hans-johnson at uiowa.edu> wrote:
> Tom,
>
> In addition to this behavior enhancement, it is also necessary to address a
> bug in the Recursive MultiResolutionPyramidImageFilter:
> http://public.kitware.com/Bug/view.php?id=8482
>
> I am in favor of changing to this default after this bug is fixed (which
> should then preserve backwards compatibility with programs that depend on
> the correct behavior implemented in bug fixes for
> MultiResolutionPyramidImageFilter in December 2008).
>
>
>
> Hans
>
> --
> Hans J. Johnson, Ph.D.
> Hans-johnson at uiowa.edu
>
> 278 GH
> The University of Iowa
> Iowa City, IA 52241
> (319) 353 8587
>
>
>> From: Stephen Aylward <Stephen.Aylward at Kitware.com>
>> Date: Thu, 5 Mar 2009 08:11:35 -0500
>> To: Tom Vercauteren <tom.vercauteren at m4x.org>
>> Cc: ITK <insight-developers at itk.org>
>> Subject: Re: [Insight-developers] Multi-resolution pyramid and
>> multi-resolution PDE deformable registration small issues
>>
>> How about making this an option?
>>
>> The default behavior can be unchanged (heck, could even throw a
>> deprecated flag and explain why).   If the option is set then the
>> deprecated flag isn't thrown and you get the behaviour you'd like.
>>
>> Option should be controlled by a member function (NOT a cmake option).
>>   Perhaps something like: AlwaysSmoothOutput or OverSmoothOutput or
>> some such...
>>
>> s
>>
>> On Thu, Mar 5, 2009 at 4:12 AM, Tom Vercauteren <tom.vercauteren at m4x.org>
>> wrote:
>>> Hi all,
>>>
>>> I just saw a few weird things in some multi-resolution objects.
>>>
>>> First of all, the MultiResolutionPyramidImageFilter will always
>>> produce a blurred image even with an all one schedule. This is because
>>> the input it always smoothed to produce the output. If the schedule at
>>> a given level is all one, the sigma of the Gaussian will be 0.5.
>>>
>>> This case is better handled in
>>> RecursiveMultiResolutionPyramidImageFilter. In that class, if the
>>> schedule is all one, the output will only be a casted version of the
>>> input. This makes more sense to me.
>>>
>>> Would anyone mind if I changed the behavior of
>>> MultiResolutionPyramidImageFilter to perform the same operation as
>>> RecursiveMultiResolutionPyramidImageFilter in the case of all one
>>> schedule?
>>>
>>>
>>> Also it seems that RecursiveMultiResolutionPyramidImageFilter should
>>> be the default image pyramid class for most applications. It is more
>>> efficient than MultiResolutionPyramidImageFilter when the schedule is
>>> downward divisible and falls back to MultiResolutionPyramidImageFilter
>>> when it is not.
>>>
>>> Would anyone mind if I changed the default image pyramid filter in
>>> MultiResolutionPDEDeformableRegistration to be
>>> RecursiveMultiResolutionPyramidImageFilter instead of
>>> MultiResolutionPyramidImageFilter?
>>>
>>> Regards,
>>> Tom
>>> _______________________________________________
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>>
>>
>>
>> --
>> Stephen R. Aylward, Ph.D.
>> Chief Medical Scientist
>> Kitware, Inc. - North Carolina Office
>> http://www.kitware.com
>> (518) 371-3971 x300
>> _______________________________________________
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