In one embodiment, {HEAD ~ obstacles} in {TAIL ~ the route area} are identified and corresponding forbidden areas are demarcated 
in
In one embodiment , { HEAD ~ obstacles } in { TAIL ~ the route area } are identified and corresponding forbidden areas are demarcated
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH