[Insight-users] Initial vector field for deformable registration

[Karthik Krishnan]

On Fri, Jul 10, 2009 at 12:59 PM, Jochen Cammin <jcammin1 at jhmi.edu> wrote:

> Should I take the silence on this subject as a sign that it is not possible
> to initialize the parameters of an optimizer other than zero?


You can initialize Demons registration with an initial deformation field.
The API is as simple as :

  demonsRegistrationFilter->SetInitialDeformationField( fieldImage );



>
> Thank you,
> Jochen
>
>
> Jochen Cammin wrote:
>
>> Hello,
>>
>> I'm fairly new to ITK and want to use it for 4D image registration. I
>> modified the example DeformableRegistration2 to my needs (changing the
>> dimension from 2 to 4) and it works well.
>>
>> I assume that the initial deformation parameters are all set to 0. In my
>> case, however, I do have an estimate for the initial deformation in
>> terms of an initial motion vector field (a 3D image with vectors as
>> pixel types). Is it possible to initialize the deformation with this
>> vector field?
>>
>> I saw that other examples (like DeformableRegistration7) explicitly
>> initialize the deformation parameters with zeros by calling
>> parameters.Fill( 0.0 ). But it is not obvious to me how I would
>> translate the vector field into deformation parameters.
>>
>> Thank you,
>> Jochen
>>
>>
>>
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-- 
Karthik Krishnan
R&D Engineer,
Kitware Inc.
Ph: 518 881 4919
Fax: 518 371 4573
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