[Insight-users] Making a deformation field denser in order to deform points

[brian avants]

see line 142 here:

https://github.com/stnava/ANTs/blob/d99d9c9e23ae17c116377a248cd370ddbd8c2599/Examples/antsApplyTransformsToPoints.cxx

you can do the same thing in your application but note that the deformation
field , when applied to a point , should be the inverse of the deformation
field applied to an image

see my previous email regarding SyN and inverse warps.


brian




On Wed, Dec 4, 2013 at 2:33 PM, Yago Diez <yagodiezdonoso at gmail.com> wrote:

> Hi everyone,
>
> I have a problem regarding itk deformation fields:
>
> Specifically, I want to know where a particular point ends up after
> registration. Said registration has produced a deformation field. I have
> already used this deformation field to deform the source image and produce
> the output image for registration (this was done using itkWarpImageFilter).
>
> My problem is that at this moment I only want to transform one point. The
> obvious solution was to read the corresponding voxel in the deformation
> field and add it to the point, but the problem is that the deformation
> field is not "dense enough", so in most cases, the read deformation for a
> point ends up being zero (see attached image for a screen capture of a 2D
> slice of my 3D deformation field).
>
>  I have noticed how when I deform an image with itkWarpImageFilter, there
> is an "extra" interpolation step which would avoid the problem I am having,
> but so far I have not been able to interpolate a deformation field. Any
> ideas on how to do that?
>
> Thank you
>
>
>
>
> Yago Diez Donoso (PhD)
> Computer Vision and Robotics Group http://vicorob.udg.es/
> E-mail: yago at eia.udg.es; yagodiezdonoso at gmail.com
> Phone: (int. code) 34 972418013
> University of Girona
>
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