[Animats]

No, Etak could recover position after you made a few turns, unless you were in a city with a very regular grid. The recent path would be matched against the map to find the best match. When Honey demoed the system to me, he drove around a vacant lot in Menlo Park to force it to lose position, and then it recovered after a few turns.

[theamk]

I am sure it could recover most of the time, in some places. I am not so sure it would work well in all places -- regular grid is pretty common for example in New York City.

You could actually see it in use if you used older GPS units -- back in SA time, the GPS was low precision (~100 meters), but still provided mostly accurate heading/velocitry information. Thus, many GPS navigators required mapmatching (see other thread for details). It would always fail on me in the most annoying moments, and would take quite a while to recover.