Map data model
The following image shows an overview of the Dynamic Map Manager (DMM) data model:
Link/Node relationship
Links
The following image shows the link in the DMM data model:
Link is an object that represents a segment of a road from the road network. The road network is split into links so that no link contains any intersections, and the shape of a link is represented as list of positions. As a result, all links are polylines and have two edges, which are called nodes.
Most links are connected with others at the node position, so an intersection corresponds to the node that is shared by two or more links. All links and nodes have unique IDs. If some links are connected, the node at the connection point has the same node ID. A road segment that is represented by a link contains one or more lanes, while a lane represents only one-lane in a road segment.
Link shapes
The following image shows the link shape in the DMM data model:
Link Shape is a list of coordinates for the positions representing a link. The node that corresponds to the first coordinate is called From Node, while the node that corresponds to the last coordinate is called To Node. The order of those coordinates is independent from the navigable direction for the one-way link.
One-way and bidirectional links
The following image shows the use of directional links in the DMM data model:
Lanes
Link/Node/Lane (Optional: if lane data is available in map)
The following image shows the link/node/lane data model:
Lanes (data model)
The following image shows the Lane data model:
Lane is an object to represent a lane in a road segment. In some use
cases, vehicles can report precise positions and need to handle lane-level information.
The data model is similar to the Link data model. Lanes in the real-world
are split into lanes in IBM® IoT Connected Vehicle Insights so
that no lane contains any intersection. As a result, all lanes are also polylines and have
two edges. Unlike with links, there is no specific data model for edges of lanes as there
is for Node in the Link data model. Instead, Lane has
connecting lanes, which are called incoming lanes and outgoing lanes.
Layers (Link-Lane conversion)
The following image shows the Layer data model:
In some use cases, contextual information on Links is fed to IBM IoT Connected Vehicle Insights, but some vehicles need lane-level information, and the opposite might be true as well. In these cases, the ROS mapping function can be used to convert the information. See Context Mapping REST API for the details.