[Insight-users] Deformation field

[Martin Urschler]

Michelangelo Paci wrote:
> Hi,
> when you obtain a deformation field from a deformable registration, this 
> field has a specific unit of measure? I think each vector represents the 
> displacement of each voxel, so, as the image is represented in micron, 
> do I've to read each vector as a micron displacement?
> Please, help me.
> It's very important.

hi

the displacement vectors that you get from itk nonrigid registration 
algorithms are always measured in the same physical coordinate system as 
your images.
e.g. if you have CT images with a physical resolution of 0.5mm in each 
dimension, your vectors will have this dimension as well.

you could look into the WarpImageFilter, there you'll see that the 
displacements are added to the !physical! coordinates of the 
image-to-be-warped and at the resulting physical location the intensity 
value for the warped image is interpolated.

regards,
Martin


-- 
Martin Urschler
TU Graz - Institute for Computer Graphics & Vision
EMail: martin at urschler.info  ICQ: 41586273
Web: http://www.urschler.info
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