I believe it will be difficult in land than it is in air or water. For e.g., how dependable would be the the recognizable features, especially in lesser known r

I believe it will be difficult in land than it is in air or water. For e.g., how dependable would be the the recognizable features, especially in lesser known roads. Without that if the vehicle narrowly misses a road (could be due to a new road coming up or slight mismatch in the map or a temporary diversion) then the direction and distance would quickly become useless as it can't place itself anymore in the maps. Human beings can use their intuition or ask someone to correct themselves, but it would be very sophisticated to implement on a self driving machine.