Autonomous cars can only understand the real world through a map
As we’ve seen in the first in the series, however numerous and multifarious, sensors do not make for automated cars alone. This is why HERE is developing an automated driving cloud that can work in conjunction with sensors to create bona fide self-driving cars. One aspect of this is the creation of ultra-precise, high definition maps that, through the cloud, can map an area down to the centimetre and constantly feed new and relevant information to the vehicle as it makes its automated journey from A to B.

Read more : http://360.here.com/2015/04/16/autonomous-cars-can-understand-real-world-map/
