In anticipation of others having the same problem I had today when I tried
to use the define spherical ROI function in Russell Poldrack's new ROI
toolbox:
The code doesn't like when you enter NMI coordinates that result in
fractional voxel coordinates. For example, I got an error message ("the
specified location is not on the grid!") when I entered the coordinate -34,
-48, 44 because the resulting voxel coordinates (given my voxel sizes) were
12.5, 17, 25.
The solution is simple: figure out the nearest NMI coordinate that will
result in a voxel coordinate that is a round number, and use that instead.
I used SPM display to display my mask, typed in the NMI coordinates, looked
to see what the equivalent voxel coordinates were, edited them so that they
were round numbers (which in turn changes the NMI coordinates), then used
those new NMI coordinates as the values on which the ROI was centered. So,
in the end, what I ended up entering was -36, -48, 44.
Best wishes,
Christy
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