Raj Rajkumar, one of the leading experts on self-driving cars at Carnegie Mellon University, said the map-based approach makes sense for a company with Google’s resources but is not required.

“Google is capable of collecting all this information. In our case, we don’t have that capability, so we have to be creative. It turns out that’s sufficient” said Rajkumar, who has developed a modified Cadillac that relies on radars, video cameras and six laser scanners and in 2013 drove 33 miles (53 km) to the local airport without human intervention or 3D maps.