Lane Geometry Model
Using the Lane Topology Model as its basis, the Lane Geometry Model provides precise 3D locations for Lane Groups, Lane Boundaries, and Lane Paths. 3D curves are published as polylines, which are an ordered set of 3D points, where each point has latitude, longitude, and elevation.
Lane Group Reference Line
Each Lane Group has a 3D polyline representing the overall geometric shape of the Lane Group. It spans from the Start Lane Group Connector to the End Lane Group Connector.
The ends of all Lane Group Reference Lines at a given Lane Group Connector are required to have consistent 3D bearing (tangent) and 3D curvature. There is no requirement for geometric continuity between Lane Group Reference Lines at adjacent Lane Groups. These lines do not have to meet, but they all must have the same bearing and curvature.
Each Lane has two 3D boundaries, one on each of its sides. For the outermost lanes, the outer boundary will coincide (at a 2D level) with the Lane Group Boundary. The outer boundaries are the left boundary of lane 1 and the right boundary of the highest-numbered lane. Other boundaries can be shared between lanes when they are adjacent: the right boundary of lane 1 is the left boundary of lane 2, and so on.
Lane Boundaries are expected to be geographically continuous across Lane Group Connectors in all 3 dimensions (latitude, longitude, and elevation).
Lane Path Geometry (Lane Drive Path)
Each Lane has a single 3D Lane Path geometry, or Lane Drive Path, representing a nominal path through the lane.
Lane Path Geometries are expected to be 3D continuous where they meet at Lane Group Connectors.
Additional Lane Geometry Constraints
All geometries at a Lane Group Connector have the same elevation where they (2D) touch the Lane Group Connector. This applies to the Lane Group Reference Lines, Lane Boundaries, and Lane Paths.