If the transform is nonlinear, then the Affine part will not give you
the exact location. To map a point in native space to some location
in MNI space, you'll need the inverse of the mapping from MNI space to
native space (which is the one used for generating the normalised
images). You can write out the inverse of the deformation via the
Deformations Utility, and simply read off the appropriate values from
the Nx x Ny x Nz x 1 x 3 volume.
Best regards,
-John
2012/4/25 Zhijiang Wang <[log in to unmask]>:
> Dear all SPMers,
>
> We all know individual images can be normalized to MNI template.
>
> But, there is a question.
> I have a physical coordinate (x1,y1,z1) mm for a voxel, so what's its MNI
> coordinate when its belonged individual image is normalized to MNI space?
>
> I found there is a variable "Affine" in "*seg_sn.mat",
> is it right to do (x1, y1, z1, 1) * Affine ?
>
> Thanks!
> --
>
> Best wishes,
>
> Ross Wang
>
> --------------------------------------------
>
> PhD Candidate
>
> Room 407, East Segment, Material Science Building,
>
> The International WIC Institute,
>
> Brain Informatics,
>
> College of Computer Science and Technology,
>
> Beijing University of Technology,
>
> Beijing, China.
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