[Insight-users] BSpline deformable transform Helper class

[Rupert Brooks]

Frederico,

I implemented a modified set of KernelTransforms including a Jacobian
a while ago that you might find useful for this problem.  I use them
for registration a lot, and have had good results.  I find the LBFGSB
optimizer works quite well with them.  With more than 10-20
parameters, Amoeba and Powells could get pretty slow.

http://insight-journal.org/midas/handle.php?handle=1926/494

Cheers,

Rupert


> You should consider to use instead any of the KernelTransform and
> making it start with some of the key points in your curve (e.g.
> points of max curvature) to be "source" landmarks. In this way your
> optimizer will be able to focus on only those N landmarks that will
> actually guide the position of the curve. The "target" landmarks could
> be initialized to be the same points mapped in to the image, and then
> the optimizer will explore new positions of the "source" landmarks.
>
>
> The bad news... is that we never got to implement the Jacobian of
> the KernelTransforms, so currently you can't use them along with
> Metrics that compute their derivatives by composing the Transform
> Jacobian with the gradient of the moving image.

-- 
--------------------------------------------------------------
Rupert Brooks
McGill Centre for Intelligent Machines (www.cim.mcgill.ca)
Ph.D Student, Electrical and Computer Engineering
http://www.cyberus.ca/~rbrooks