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