[Insight-users] DeformationFieldTransform vs LandmarkBasedTransformInitializer

[Dawood Al Masslawi]

David,

You can do a landmark-based registration using the IterativeClosestPoint
method

included in the ITK, you can also use the kernel transforms in a
registration framework

to do a non-rigid registration.

If you are to use the kernel transforms note that the Jacobian is not
implemented in the

current classes so you can only use them with the 1+1 and Amoeba optimizers
(or any other

optimizer that doesn't need derivation), however you can use an alternative,
that is a contribution

made by Rupert Brooks to the Insight Journal (http://hdl.handle.net/1926/494)
which introduced some

improvements to the kernel transform class and its subclasses, namely
implementing the Jacobian.

It's computation is slow so you should probably use it with high speed
metrics (e.g. mean square)

and optimizers. It's similarly implemented in the Elastix (elastix.isi.uu.nl
).

Also recently I came across another ITK-based implementation in the
Plastimatch project

(plastimatch.org), their lanmark-based registration supports 3 types of
Radial Basis Functions,

Thin-Plate Spline (global registration), Gaussian (infinite support) and
Wendland (compact support, local

registration).

As for the DeformationFieldTransform, I agree. It only seems logical that it
would support the more general

transforms comparing to the LandmarkBasedTransformInitializer. In addition
the DeformationFieldTransform

has a GetInverse method which might come in handy sometime :)

Best regards,

Dawood


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Are these the only two classes to do landmark based registration in ITK?

I noticed that LandmarkBasedTransformInitializer can only compute a
rigid transform while DeformationFieldTransform seem to use a more
general transform - is this the intended difference?

Thanks,

David
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