Technology companies are racing to develop ultra-precise digital maps that can guide self-driving cars within inches of where they should be.
Developers say better maps will help the auto industry deliver on its promise of widespread use of driverless vehicles.
The new tech will provide extra details such as trees and pedestrians.
It promises to be off by no more than 25 centimeters.
That would be a big improvement over satellite-based GPS, which is used by ships, aircraft and increasingly by drivers or on mobile phones but can be off by up to 20 meters, especially inside buildings or underground.
The developers say the improved mapping technology likely will be used first in vehicles in isolated areas such as warehouses, or it might be used to help drivers of vehicles that aren't entirely autonomous.
The challenges and dangers of autonomous vehicles were highlighted in March when a self-driving Uber SUV being tested on a street in suburban Phoenix struck and killed a pedestrian.
Autonomous, or even semi-autonomous, driving will require sensors, radars, cameras and computer software to handle acceleration, braking, and steering normally done by human drivers.
This will require precise and accurate information about not just road lanes but repairs, traffic lights, crosswalks and buildings.
On a computer screen, such maps are masses of tiny points swimming around in virtual 3D, defining a landscape of trees, roads, signs, buildings, cars and pedestrians.
Data is collected by special vehicles carrying sensors and cameras. Those have drivers for now, but at some point autonomous vehicles are expected to take over.
"For autonomous driving, 3D high-precision maps will be very important, allowing cars to know their positions accurately and also know what the roads are like ahead," says Yasuhide Shibata, senior general manager of Mitsubishi Electric.
"In order to remove GPS errors, we are offering a data correction transmission service that removes GPS error so that users can know their exact location down to the centimeter. Mitsubishi Electric is developing a receiver that can locate your position within 25 centimeters when using this transmission service" he adds.
Starting in November, Japan will also get positioning information from its government satellites, including three launched last year, called QZS, Quasi-Zenith Satellite System.
Japan wants driverless cars on the roads by 2020, with hopes the Tokyo Olympics will showcase its technological prowess the way the 1964 Tokyo Summer Games displayed its new bullet train to the world.
But mapping services are popping up everywhere. Even Japanese automakers are also wooing mapping services other than the national brand.