afni.nimh.nih.gov

Well, actually, my smarter colleagues here have determined that there actually is a problem with the way 3dmaskdump works if the voxels are sub-mm (there is an int-to-float conversion problem internally). So, running my previous example above with a 0.25 x 0.5 1 mm**3 voxel dset (as opposed to 1x2x4 mm**3 dset in my example above) will *not* produce a sphere.

Fixing this is underway... Thanks for the question!

--pt