Lane-Level Localization · 1/2
Why GPS alone isn't nearly good enough
Consumer GPS is typically accurate to within a few meters, which is fine for turn-by-turn directions but nowhere near good enough to know which lane a car is in, whether it's centered in that lane, or exactly where an intersection stop line falls. A self-driving car needs localization accurate to a matter of centimeters, consistently, to make safe decisions about lane position, following distance, and where to stop.
GPS signals can also degrade or vanish entirely in places that matter most for driving: dense urban canyons between tall buildings, tunnels, and covered parking structures. A self-driving system that depended on GPS alone would lose reliable positioning in exactly the environments where precise localization is most critical.