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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Graham Wideman
March 25, 2004 09:12PM
Quick clarification needed on 3dTagalign's operation:

What are the details on how 3dTagalign uses tags, and specifically how many tags does it use (all of those provided, or just a subset?), and does it use only the tags or does it pay attention to some other features?

Puzzle: We tried it with 5 tags, and observed the RMS total pairwise tag distances, both before and after alignment as reported by 3dTagalign. FWIW, the before figure was about 15 mm, and after about 1 mm.

Then we deleted one tag in each volume, and re-ran 3dTagalign. Now the before and after RMS values *increased* to about 16 mm and 1.4 mm.

How is this possible? Surely fewer tags can only *decrease* the RMS value, both before and after?

FWIW, we used 3dTagalign with parameters:
master matvec prefix verb

Thanks,

Graham

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3dTagalign

Graham Wideman March 25, 2004 09:12PM

Re: 3dTagalign

Graham Wideman March 29, 2004 03:52PM