Im losing data when I use the “Nudge” plugin on functional datasets!?
Each dataset is defined over a 3D rectangular volume. When you nudge it, some data will be shifted out of that volume and will be lost. (Conversely, data that “comes in from outside” will be zero.) This is particularly visible when nudging functional overlays atop an anatomical underlay, which is usually defined over a larger 3D volume than the functional dataset. To avoid this problem, you can use the 3dZeropad program (or the Dset Zeropad plugin) to pad the outside of the functional dataset with planes of zeros. Then the functional dataset will be defined over a larger volume, and small shifts won’t send the nonzero data outside of this volume. An alternative would be to nudge the anatomical dataset to be aligned with the functional. This might be better, since the usual 3D whole-head images have plenty of slop space around them. If you do this in +orig coordinates (the only logical place), you should do it before you do Talairach markers, since their coordinates are not altered by t
