high-res maps help localize the vehicle. All of the sensors on the car (cameras, GPS, radar, lidar, sonar) all have some degree of error, and have their own res

high-res maps help localize the vehicle. All of the sensors on the car (cameras, GPS, radar, lidar, sonar) all have some degree of error, and have their own respective strengths and weaknesses. In order to know where the car is located at any given time, the vehicle uses data from the gps and a combination of any of the other sensors to help localize itself in the world. Relying on just GPS is risky and error prone, so fuzing that position with matching landmarks from the field of view, or lidar is a way to improve positioning. This is especially important for determining which lane the vehicle is in, where it needs to be in order to take a proper exit or turn, and what potential obstacles or traffic scenarios it might encounter depending on where it is located on a road.