[Insight-users] Re: Deformable Registration Final Parameters

[Luis Ibanez]

Hi Kevin,

The parameters of a BSpline are the components of the deformation
vector on the nodes of the BSpline grid.

The first N values are the X component of the N nodes,
The second N values are the Y components of the N nodes,...

and so on.


 From the Doxygen page of this Transform:
http://www.itk.org/Insight/Doxygen/html/classitk_1_1BSplineDeformableTransform.html


"The parameters for this transform is N x N-D grid of spline 
coefficients. The user specifies the parameters as one flat array: each 
N-D grid is represented by an array in the same way an N-D image is 
represented in the buffer; the N arrays are then concatenated together 
on form a single array."


In all image registration methods in ITK, the resulting parameters
are *EXACTLY* the same parameters that you need to set in the transform
that you connect to the Resampling image filter, in order to resample
the Moving image into the coordinate system of the Fixed image.


Please read the introductory sections of the "Image Registration"
chapter in the ITK Software Guide:


     http://www.itk.org/ItkSoftwareGuide.pdf




    Regards,



        Luis



----------------
Kevin Ming wrote:
> Hello,
> 
> What do the 'final parameters' in a b-splines deformable registration 
> represent (I'm using DeformableRegistration7.cxx, revision 1.8)?  I was 
> under the impression that the if I were to apply those parameters to an 
> image via a b-splines warping algorithm (in this case, 
> BSplineWarping1.cxx, revision 1.11) I would be be able to get an output 
> image from the registration.  But this was not the case for me.
> 
> That is, if I were to register image ' Fixed' to image 'Moving' using 
> DeformableRegistration7.cxx, and using the final parameters from that 
> registration on image ' Fixed' via BSplineWarping1.cxx, I'd be able to 
> get an image that looks approximately similar to image ' Moving'.  Or 
> does it work the reverse order?  But actually I've tried both ways and 
> was unable to obtain what I was expecting.
> 
> 
> Thank you,
> Kevin