[Insight-users] problem with deforamtion field from DeformableRegistration15.cxx

[Hegenbart, Lars]

Hi Pinpress,

maybe some more information could help to clarify your question.

Does your output look ok?, Does it mean, you can see a deformation?

Does your image coincide with the deformation grid? If so, I can imagine the BSplines will not interpolate. Is that what you observed to be rigid?

What do you mean by "vectors do not make sense"? Can you give an example?

Regards
Lars


-----Ursprüngliche Nachricht-----
Von: insight-users-bounces at itk.org [mailto:insight-users-bounces at itk.org] Im Auftrag von pinpress
Gesendet: Mittwoch, 22. Oktober 2008 17:48
An: insight-users at itk.org
Betreff: [Insight-users] problem with deforamtion field from DeformableRegistration15.cxx


Hi,

I was able to compile the example program DeformableRegistration15.cxx (I
did not modify the example cxx source code), which performs rigid, affine,
and BSpline registration sequentially. The program also gives output image
as expected. However, in my application I need to get the deformation field.
I was able to read in the deformation field VTK file into Matlab, however, I
have trouble interpreting what it is exactly. For example, if my input
images are both of 3D matrix, 10-by-10-by-10. The deformation field I got
would be:

10-by-10-by-10-by-3

Which clearly tells that each voxel, there is a 3D displacement vector.
However, the displacement vectors just does not make sense. I was able to
verify that this displacement field is exactly a "rigid" deformation -- it
does not have any nonrigid component, but clearly the images were nonrigidly
deformed. So, what I am doing wrong here? 

By the way, I used the same analysis to the deformation field generated from
DeformableRegistration5.cxx (which is just a LevelSet registration, without
rigid or affine registration pre-processing), the displacement vectors do
make sense -- I can clearly see nonrigid deformation.

Thanks very much in advance for help.
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