• 3. Navigation Map vs. HD Map
• 4. Localization, Perception, Planning with Maps
  • 4.1 Localization
  • 4.2 Perception
  • 4.3 Planning with maps
• 5. Apollo HD Map
• 6. Apollo HD Map Construction

3. Navigation Map vs. HD Map

Autonomous vehicles lack the innate visual and logical capabilities of human drivers. A high definition map contains a huge amount of driving assistance information,The most important information is：

• the accurate three-dimensional representation of the road network, for example,the layouts of intersections and the locations of signposts.
• A high definition map also contains a lot of semantic information,The map might report what different colors of traffic lights mean.

One of the most important features of a high definition map is precision.

4. Localization, Perception, Planning with Maps

High definition maps are at the core of the Apollo self-driving platform.This is because many other self-driving modules depend on the high definition map.

4.1 Localization

just for example, We can find the landmarks using data collected from different types of sensors, The vehicle compares the data it collects with the known landmarks from its high definition map.

This matching process is a complex chain that requires preprocessing,coordinate transformation,and data fusion.

1. Preprocessing eliminates inaccurate or poor quality data.
2. Coordinate transformation converts the data from different perspectives into a uniform coordinate systerm.
3. Data fusion merges data from different vehicles and different types of sensors.

Once the autonomous vehicle determines its position with high precesion, the localization task is complete.

The entire localization process depends on the map which is why the vehicle needs high definition maps in order to know where it is in the world.

4.2 Perception

The self-driving car can also use the high defintion map to help with perception. Self-driving car sensors have limitaions, Camera,lidar and radar all have limits on their ability to detect objects beyond a certain distance. In bad weather or at night a sensor’s ability to recognize obstacles might be limited even further. In such circumstances a high definition map helps a lot,

• It can feed traffic light positions to the rest of the software stack even if the sensors can’t detect the traffic light yet.This can help the car’s next decisions.
• Another benefit is that the map will help the sensor narrow it’s detection scope.

4.3 Planning with maps

A high definition map helps our vehicle find suitable driving space. For example, a high definition map helps the vehicle identify the exact center line of a lane on the road,That way,the vehicle can drive as close as possible to the center. A high-definition map can help the vehicle narrow its options so that it can select the best maneuver.

5. Apollo HD Map

Apollo HD maps use the OpenDRIVE format in industry-wide mapping standard.OpenDRIVE is like an API that makes it easy for everyone to read the same map data.

Standard OpenDRIVE vs. Apoll OpenDRIVE

6. Apollo HD Map Construction