[Insight-users] 3D free form registration with ITK

[Todd Jensen]

> From: Ali Sadeghi 

> Subject: [Insight-users] 3D free form registration with ITK
>
> I'm just trying to use ITK for a 3D free form registration (rigid + affine +
> Bspline).  The registration was done good, but the algorithm corrupt the
> first and last slices of the 3D image in the output of the registration,
> most parts of these two slices were filled up with the background default
> value. Has anyone else encountered with such a problem and if yes how could
> you solve it?

I don't think this is a corruption, but an artifact from the transformation/interpolation. The interpolator is not finding all the required pixels for the interpolation in the moving image for the location in the fixed space.  It probably needs a pixel that is at index -1 or n in the 3rd dimension (assuming you have n slices).

One way I found around this is to create a temporary moving image that is n+2 slices, paste the original moving image into 1 to n. But this results in partial volume artifacts from interpolation - another issue to solve.

Todd Jensen