[Insight-users] Re: deformable registration

[Luis Ibanez]

Hi Silvester,


It depends on what deformable registration method you use from ITK.


A) Demons
B) FEM
C) BSpline transform
D) KernelSpline transform


In the case of  DEMONS and FEM, you get ast output a deformation field.
Using this deformation field you could identify the displacements of
particular points in the moving image.

These two methods, however will not use any landmark information
during the registration process. In practice you can simply connect
an observer to the registration and at each iteration print out the
displacement vectors corresponding to your set of landmarks.


In the case of BSpline transforms used with the basic registration
framework, you can use the BSpline transform as computed at each
iteration of the optimization process, and again map a set of
landmarks in  order to evaluate their displacements.  The landmarks
will not be used for stering the registration process, they will
only be probes / observers that will allow you to see how the
registration is progressing.


In the case of KernelBase transforms, like the ThinPlate spline
and its family, you actually use landmarks as part of the registration
process. In this context you could associate your landmarks to
the source and target landmarks used by the transform.  The optimizer
will update the coordinates of these landmarks in order to optimize
the image metric.



Please let us know if you have further questions,


Thanks


   Luis


--------------------------
Silvester Czanner wrote:

> Hi Luis,
> 
> I have two grayscale volumes, which I would like to register using 
> deformable registration methods from ITK.
> Is it possible in ITK to localize some correspondent landmarks before 
> deformable registration and during the registration process to track the 
> trajectories of those landmarks?
> 
> Silvester
>