¥Quick outline of procedure:
1.On the main AFNI control
panel, set the anatomical underlay dataset (with [Switch UnderLay]) to be what you want to draw on -- usually a SPGR or MP-RAGE type of
dataset
åi.e., the anatomical
underlay will serve as our guide or template for drawing the ROI mask
2.Start the Draw Dataset plugin (this is our ROI-creating plugin):
å [Define Datamode] ¨ [Plugins] ¨
[Draw Dataset]
3.Create an all zero
anatomical overlay dataset with the Draw Dataset plugin. This is the beginning of our ROI
mask. At this point, the
anatomical overlay is empty - i.e.,
all the voxel values are zero
åThis anatomical
overlay must have the same geometry as the anatomical underlay, i.e.,
it has the same voxel size as the underlay, the same xyz-grid spacing, etcÉ, since drawing/editing is done on a voxel-by-voxel basis
íThink of the anat
overlay as a blank piece of tracing paper that is the same size as the template
underneath. The blank overlay will be used to trace portions of
the underlay. Voxels inside the
traced portion will make up the
ROI mask. Values outside the
traced region are irrelevant
(zeros)
åNote: You could also
edit an already-existing ROI mask (that you created earlier) at this
step