{TAIL ~ The method} 1 wherein the step of comparing includes generating an output corresponding to a 3 D position of {HEAD ~ any said obstacle} relative to said 3 D reference model 
{ TAIL ~ The method } 1 wherein the step of comparing includes generating an output corresponding to a 3 D position of { HEAD ~ any said obstacle } relative to said 3 D reference model
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH