Adding motion parameter files together

AFNI Message Board
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AFNI version info (afni -ver): Version AFNI_23.0.07 'Commodus'

Hello,

If I run two 3dvolreg algorithms back to back, and get two dfiles of the motion parameters; is it safe to say I can just add the respective values in these files to get the total motion parameter of the two? I hope that makes sense. Thanks in advance!

Cheers,
Edwin

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Hi Edwin,

Yes, dfiles for multiple runs can be concatenated. However, we apply them as per-run regressors, so they are broken apart for that.
See how afni_proc.py does it: https://afni.nimh.nih.gov/pub/dist/edu/data/CD.expanded/AFNI_data6/FT_analysis/s15.proc.FT.uber.NL, tracking dfile_rall.1D and then mot_demean within the script.

  • rick