3dmaskdump values vs gui values

AFNI Message Board
1

Hi,

I am trying to dump out coefficients and t-statistics at certain coordinates, using 3dmaskdump. Specifically:
3dmaskdump -nbox -49 -6 7 -o output.txt -xyz stats.AControl1+tlrc’[21…37]’

The output of this gives me the xyz coordinates 49 5 8. I understand that these are in RAI order instead of LPI, which explains the sign reversal, but it seems that the actual coordinates are slightly different too. Is this because of the resolution of the data? I am also confused because if I jump to this coordinate (-49 -6 7) in the afni gui, I can, and I get different coefficient and t-stat values (in OLay) than what are dumped into my text file. Maybe this is an average of the nearest voxels and not an actual data point? Some clarification about what is going on here would be greatly appreciated!

Thanks!

-Lexi

2

Hi Lexi,

Note that the 2 sets of coordinates are a little different.
That is probably because in the GUI, the overlay dataset is
being resampled to match the underlay dataset. Jumping to
coordinates in the GUI is based on the underlay.

Basically, they should match if you set the Underlay dataset
to be the same as the Overlay one.

  • rick