[Insight-users] warping a clound of points when the target landmarks form a straight line

[Ramón Casero Cañas]

On 20/06/11 14:51, Ramón Casero Cañas wrote:
>
> Yes, the correspondence is one-to-one. I had actually bumped into your
> itk::BSplineScatteredDataPointSetToImageFilter class, but I hadn't
> realised it can be used for warping. Thanks for the pointer, I'll
> definitely give it a try!


Hi Nick,

Sorry for the delay, I have been out of my office.

I have been trying to make this work, and I have bumped into a problem.

As you suggested, I define the warp as an R^3 -> R^3 mapping.

x -> (y-x)

where x, y are the source, target landmarks, respectively.

Now I have an image where each voxel is the interpolated value of the 
warp field.

How can I sample the image at specific points? What I want, in the end, 
is a function


yi = bspline_warp(x, y, xi)

where xi are some points to be warped to yi.


In the documentation of ITK v4.0, there's a class 
BSplineControlPointImageFunction

http://www.itk.org/Doxygen/html/classitk_1_1BSplineControlPointImageFunction.html#details

that seems to be ready for this. However, in the current stable release 
v3.20, that class is not present

http://www.itk.org/Doxygen320/html/files.html

Is there a nice way of doing the sampling without having to move to the 
development release of ITK?

Best regards,

Ramon.

-- 
Dr. Ramón Casero Cañas

Computational Biology
Department of Computer Science
University of Oxford
Wolfson Building, Parks Rd
Oxford OX1 3QD

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