[Insight-users] Question about generating and composing deformationfields

[M.Staring at lumc.nl]

Hi Anja,

I think you need two things:

1) A transform that combines multiple sub-transforms
2) The TransformToDeformationFieldSource in the Review directory to
compute the deformation field from the composed transform.

For the first point you can use the CombinationTransform classes
distributed with elastix (http://elastix.isi.uu.nl) also described in
the Insight Journal (http://hdl.handle.net/1926/197). You can choose to
use addition or composition with the functions SetUseComposition() or
SetUseAddition(). Checkout the elastix manual for the difference between
adding and composing, and what is advisible.

Hope this helps,

Marius

> 
> Hello everyone,
> 
> I have a series of affine and non-rigid transformations and 
> what I would like to do is create one single deformation 
> field by combining these deformations and then use this final 
> deformation field to resample my image.
> 
> So I need to do two different compositions (I am not sure if 
> I should compose or add these deformation fields. The 
> formulation of composition is not completely clear to me as well).
> 
> 1: I have an affine transformation and a non-rigid 
> transformation. So, given an initial image, how can I create 
> a deformation field that encapsulates these two transformations.
> 2: I have a non-rigid transformation followed by an affine 
> transformation. Again, I would like to create a deformation 
> field that encapsulates them.
> 
> I would be very grateful if anyone could point out how I 
> might achieve this in ITK. Also, maybe more experienced 
> people doing medical image registration could share some 
> information on how deformation foelds are combined (addition 
> vs composition)
> 
> Many thanks for any help you can give me,
> 
> Anja
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