https://phys.org/news/2018-12-app-self-driving-car.html

The newly developed technology enables a self-driving car to automatically produce and update a precise map to apprehend the environment surrounding the road. The map has an error range of less than 10 centimeters, which is outstanding in world standard.

The key technology uses sensors to recognize the surrounding environment on the road, creating and updating precision maps. Rather than ordinary maps, automated driving requires "precision maps" that include traffic lights, boundary stones, landmarks, and other parts of the driving environment. It is crucial that this information is updated in as close to real time as possible.