[Insight-users] Question about new BsplineTransform control grid

[M. Okan Irfanoglu]

Hello,

I had a quick question about the control BsplineTransform control point
locations for B-Splines elastic registration in ITKv4.


Basically, what I would like to do is the following:


While registering two 3D MR images using BSpline transformation, sometimes
because of the noise behaviour in the background, we get very weird
deformations in the background regions. This is a known problem with this
type of registration and there are papers out there that deal with it by
adding a regularization term to the optimization function.

In our case, especially in these background noise regions, the Jacobian of
the transformation act very weirdly (with very large or very small values)
and if you manipulate the image signal after deformation with these
Jacobians, the effect can even go inside the brain region slightly from the
sides.


What i would like to do is:
1) To provide a brain mask to the registration routine.
2) Using this mask and the results of an initial registration without the
mask, constrain the the B-Splines control points parameters falling in the
background noise region using some regularization.
3) to do this, I need to extract the exact locations of the B-Spline
control grid points and with ITKv4, I do no know how this can be done. I
know with the previous version, the node (1,1) was placed in the first
voxel and the rest was straightforward but I do not know how I can get the
exact BSpline control points locations now.


Any help would be appreciated.

Thanks and regards.


Okan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20120127/0913555a/attachment.htm>