Reference terrain altitude maps are converted by a reference map transformation to data which correlates {HEAD ~ the reference map} to {TAIL ~ the altitude} of the missile 
Reference terrain altitude maps are converted by a reference map transformation to data which correlates { HEAD ~ the reference map } to { TAIL ~ the altitude } of the missile
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH