[Insight-users] question about b-spline field to a dense deformation field: BSplineDeformableTransform

[Anja Ende]

Thank you Nick. That makes sense. I understand how it works now :)

Anja

On 15 December 2011 20:31, Nicholas Tustison <ntustison at gmail.com> wrote:
> Hi Anja,
>
>> My question is that say we want to extract a dense deformation field
>> from this parameterised deformation field. Then each voxel is affected
>> by a few control points. Do we basically add contributions from each
>> of the control points to obtain the final deformation at each voxel?
>
> Yes, the B-spline interpolated deformation value at a point within the
> transform domain is calculated by summing the weighted contributions
> of the 16 neighboring control points and corresponding B-spline basis-
> functions evaluated at that point (for spline order = 3).
>
>> Is that what ITK does when we resample an image using this transformation?
>
> The resampling operation is agnostic with respect to the mechanisms of
> the transformation itself.  The resampling filter simply queries the transform
> as to how the point under consideration is mapped.
>
> Nick
>



-- 
Cheers,

Anja