AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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rick reynolds
February 10, 2008 06:02PM
Hi Aimee,

The directional signs, as well as the Talairach orientation
that afni uses by default (either of which you can change, of
course) are based on the Dicom orientation, RAI. That RAI
orientation means right, anterior and inferior are the negative
directions. It also means that the origin is at the most right,
anterior and inferior voxel.

Note that even if a dataset is stored in LPI orientation, for
example, the signs of the voxel coordinates still come from RAI
(unless you change that). So even though the A/P axis goes from
posterior to anterior (in this example), anterior is reported as
negative, by default.

---

On a related thought, I suggest that when you report coordinates,
you don't use signs at all, because they are at the whim of whichever
software package that you obtain them from. Report something like
23R 17.2A 6.3S, as it is not ambiguous, whereas -23, -17.2, 6.3 is.

- rick

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Subject Author Posted

y axis in tlrc space

Aimee February 10, 2008 04:34PM

Re: y axis in tlrc space

rick reynolds February 10, 2008 06:02PM

Re: y axis in tlrc space

Aimee February 11, 2008 10:03AM