That is, upon detecting a change in viewpoint , {HEAD ~ the image} of {TAIL ~ the person} changes 
of
That is , upon detecting a change in viewpoint , { HEAD ~ the image } of { TAIL ~ the person } changes
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH