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help > RE: x axis or y axis to flip hemispheres?
Nov 29, 2017 05:11 PM | Alfonso Nieto-Castanon - Boston University
RE: x axis or y axis to flip hemispheres?
Hi Gol Mi
A pure rotation will not "flip" the left-right hemispheres without also flipping either the anterior-posterior direction (a 180-degree rotation around the z-axis) or the inferior-superior direction (a 180-degree rotation around the y-axis). If you want to purely flip the left-right hemispheres without affecting anything else I would use a pure reflection along the left-right direction instead (in CONN preprocessing steps this is called a "non-rigid reflection along x-axis (x/y/z to -x/y/z)"
Hope this helps
Alfonso
ps. to clarify, the "x/y/z" axes typically point towards the "right/front/up" of the head
Originally posted by gol mi:
A pure rotation will not "flip" the left-right hemispheres without also flipping either the anterior-posterior direction (a 180-degree rotation around the z-axis) or the inferior-superior direction (a 180-degree rotation around the y-axis). If you want to purely flip the left-right hemispheres without affecting anything else I would use a pure reflection along the left-right direction instead (in CONN preprocessing steps this is called a "non-rigid reflection along x-axis (x/y/z to -x/y/z)"
Hope this helps
Alfonso
ps. to clarify, the "x/y/z" axes typically point towards the "right/front/up" of the head
Originally posted by gol mi:
Hello all,
1- Would you please let me know if I have to rotate along x-axis or y-axis to flip left and right hemispheres in MRI and fMRI images, to get affected and unaffected hemispheres?I believe the rotation should be along y- axis , however I read in one of the other posts in same forum that it should be along x- axis. But if we rotate along x-axis, the left and right will not be rotated, but just front and back will be swapped ! Am I missing something?
2- what should be the degree to rotate to flip left and right hemispheres to get affected/unaffected hemispheres? 90 or 180 degree? I think 180 degree, just wanted to make sure.
Thank you,
1- Would you please let me know if I have to rotate along x-axis or y-axis to flip left and right hemispheres in MRI and fMRI images, to get affected and unaffected hemispheres?I believe the rotation should be along y- axis , however I read in one of the other posts in same forum that it should be along x- axis. But if we rotate along x-axis, the left and right will not be rotated, but just front and back will be swapped ! Am I missing something?
2- what should be the degree to rotate to flip left and right hemispheres to get affected/unaffected hemispheres? 90 or 180 degree? I think 180 degree, just wanted to make sure.
Thank you,
Threaded View
| Title | Author | Date |
|---|---|---|
| gol mi | Nov 23, 2017 | |
| Alfonso Nieto-Castanon | Nov 29, 2017 | |
| gol mi | Dec 15, 2017 | |