“If we want to have autonomous cars everywhere, we have to have digital maps everywhere,” said Amnon Shashua, chief technology officer at Mobileye, an Israeli company that makes advanced vision systems for automobiles.  Creating them, however, is a monumental task. There are more than four million miles of roads in the United States. And compared with the maps used by GPS and navigation systems, the level of precision must be much greater. Navigational maps typically locate a car’s position within several yards. Digital maps for autonomous cars must know the locations of cars, curbs and other objects within about four inches.