[elastix] Changes in ITK's BSpline transform

Rômulo Pinho romulo.pinho at lyon.unicancer.fr
Mon Jan 16 11:49:07 CET 2012


Hi, Stefan, thx for the reaction.

For these tests, we were using ITK 3.20. We haven't yet checked the 
results with ITK 4.0. Would you suggest to do so?

Kind regards,
Rômulo

On 01/15/2012 02:51 PM, Stefan Klein wrote:
> Hi Romulo,
> Thanks for the clear explanation.
> Which version of ITK did you take the B-spline transform 
> implementation from, for your own framework?
> Kind regards,
> Stefan
>
> On 22/12/2011 17:18, Rômulo Pinho wrote:
>> Hi, Stefan, thx for the reaction.
>>
>> We compare metric values per iteration of the optimialsozer and 
>> resulting images and jacobians of the deformation fields.
>>
>> We have a class that extends ITK's BSpline transform and a program 
>> option to either use this class or itk::BSplineDeformableTransform. 
>> Our extension is nothing but an optimization to interpolate the 
>> BSpline using look up tables. As we'd expect, switching between the 
>> two classes causes barely no difference on the results.
>>
>> We managed to import our transform into elastix's (4_05) framework 
>> and checked that it gives exactly the same result with either our 
>> framework or elastix's. But when we switch to 
>> AdvancedBSplineTransform, we see a small, yet noticeable, difference 
>> in the per-iteration metric values. In the end, the jacobians of the 
>> deformation fields are similar, but we can clearly see the areas 
>> where they differ. We'd in reality expect to have the same (lack of) 
>> difference described in the case above.
>>
>> I've attached parameter files for you to see what we're using and 
>> also the log files with the per-iteration metric values.
>> If you need more info, just ask!
>> Kind regards,
>> Rômulo
>>
>>
>> On 12/22/2011 04:21 PM, Stefan Klein wrote:
>>> Hi Romulo,
>>>
>>> We made a few changes to solve the following bug:
>>> http://public.kitware.com/Bug/view.php?id=10029
>>>
>>> How did you compare the two implementations exactly? Did you make 
>>> sure to define the grid in the same way?
>>>
>>> Which version of ITK did you take the Bspline transform from? And 
>>> which version of elastix?
>>>
>>> Kind regards!
>>> Stefan
>>>
>>> On 15/12/2011 17:36, Rômulo Pinho wrote:
>>>>
>>>> Hello,
>>>>
>>>> We've been experimenting with different combinations of metrics, 
>>>> optimizers, and transforms, using elastix and our in-house registration
>>>> framework (also an ITK extension).
>>>>
>>>> We've noticed a small difference between the results we get when 
>>>> using your implementation of the BSpline transform and the native 
>>>> BSpline transform of ITK. As far as we could see (and also 
>>>> according to what you said in 
>>>> http://lists.bigr.nl/pipermail/elastix/2011-January/000321.html 
>>>> <https://webmail.lyon.fnclcc.fr/exchweb/bin/redir.asp?URL=http://lists.bigr.nl/pipermail/elastix/2011-January/000321.html>), 
>>>> there doesn't seem to be a big difference between the two to 
>>>> explain the different results we get. Could you please tell us what 
>>>> modifications you have made to ITK's transform?
>>>>
>>>> Thanks in advance.
>>>> Kind regards,
>>>> Rômulo
>>>>
>>>> --
>>>>
>>>> Rômulo PINHO
>>>> Post-doc Research Engineer
>>>> Centre Léon Bérard
>>>> 28, rue Laennec 69373
>>>> Lyon, France
>>>> +33 (0)4 78 78 51 50
>>>> romulo.pinho at lyon.unicancer.fr
>>>> http://www.creatis.insa-lyon.fr/rio/RomuloPinho 
>>>> <https://webmail.lyon.fnclcc.fr/exchweb/bin/redir.asp?URL=http://www.creatis.insa-lyon.fr/rio/RomuloPinho>
>>>>
>>>>
>>>> _______________________________________________
>>>> elastix mailing list
>>>> elastix at bigr.nl
>>>> http://lists.bigr.nl/mailman/listinfo/elastix
>>>
>>> -- 
>>> Stefan Klein
>>> +31 10 7043049
>>> http://www.bigr.nl/people/StefanKlein
>
> -- 
> Stefan Klein
> +31 10 7043049
> http://www.bigr.nl/people/StefanKlein
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