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What is Lanelet2?

Lanelet2 is an open HD map format and C++ library originally developed by the FZI Research Center for Information Technology and now widely used as the HD map representation in Autoware and many research stacks. Its central idea: roads are bundles of small “lanelets”, each bounded by a left and right linestring, with explicit topological and regulatory relations.

The original Lanelet2 paper (Poggenhans et al., 2018) is a good primer.

What a Lanelet2 map looks like

Section titled “What a Lanelet2 map looks like”

Physically, a Lanelet2 map is an OpenStreetMap XML file with extra tags. That gives you:

  • Nodes — single points (latitude, longitude, optional elevation).
  • Ways — ordered sequences of nodes. In Lanelet2, ways act as lane boundaries, stop lines, traffic light supports, and more.
  • Relations — typed groupings. A lanelet relation pairs a left and right way and may carry attributes for speed limit, road type, one-way flag, etc.

On top of this, Lanelet2 ships with a routing graph, regulatory elements (traffic lights, right-of-way, speed limits, stop signs), and geometric utilities.

Lanelet2 vs OpenDRIVE

Section titled “Lanelet2 vs OpenDRIVE”

Both describe HD maps but optimise for different sides of the AV stack:

AspectLanelet2OpenDRIVE
GeometryPolylines (linestrings)Analytical (arc, spiral, polynomial)
TopologyExplicit lanelet adjacency / sequenceLane sections + junction connections
Native consumersAutoware, planning research, ground truthSimulators (CARLA, esmini, RoadRunner)
File formatOSM XMLBespoke XML
Editing ergonomicsReasonable to hand-edit small areasHard to hand-edit at any scale

Lanelet2 is generally simpler to inspect by hand. OpenDRIVE is more precise for simulator consumers.

Common authoring tools

Section titled “Common authoring tools”
  • TIER IV Vector Map Builder — a free browser-based Lanelet2 editor designed for Autoware. Lane authoring with regulatory elements (traffic lights, stop lines, crosswalks, parking, …) and point cloud reference layer. Often the first recommendation for new Autoware users today.
  • JOSM with the Autoware Lanelet2 plugin — the classic OSM desktop editor extended for Lanelet2. Mature and powerful; Autoware-compatible output sometimes needs manual fixup.
  • Hand-edited OSM XML — viable for small fixes, painful at scale.
  • drawtonomy — imports a Lanelet2 .osm file for visualization and basic geometry edits, with round-trip export.

Where drawtonomy fits

Section titled “Where drawtonomy fits”

drawtonomy is a 2D, browser-based Lanelet2 editor. It is not a Vector Map Builder or JOSM replacement for city-scale or survey-grade authoring, but it covers a complete 2D editing loop:

  • Imports a Lanelet2 .osm and renders lanelets as editable Lane / Linestring shapes.
  • Lets you reshape boundaries, edit lane connections, and place regulatory elements — traffic lights, traffic signs (including speed limits), stop lines, and right-of-way — linked to the lanelets they govern.
  • Re-exports to Lanelet2 OSM. Original IDs, tags, and regulatory elements you didn’t touch round-trip verbatim through a sidecar mechanism; edits you made are written natively in the new file.
  • Useful for inspection, teaching, figure preparation (papers, slides), and authoring small-to-medium scenes.

Where the 2D, browser-based model shows its limits:

  • 3D detail — elevation, banking, bridges, grade separation. drawtonomy’s canvas is 2D.
  • City-scale or survey-grade authoring against LiDAR / aerial imagery. Vector Map Builder supports tracing on top of a point cloud reference layer; drawtonomy does not.
  • Bulk operations across thousands of lanelets — no filters, no batch edits.

For city-scale or LiDAR-aligned authoring, Vector Map Builder (for Autoware-targeted maps) or JOSM (for general OSM-style editing) remain the right tools.

Section titled “Related reading”