What is an HD map?

An HD (high-definition) map is a centimetre-accurate, machine-readable description of the road network — lane boundaries, lane connections, regulatory elements, reference geometry — designed to be consumed by an autonomous driving stack rather than read by a human driver. HD maps are one of the load-bearing inputs to most production self-driving (AV) and advanced ADAS systems.

This page is a neutral primer on HD maps for autonomous driving, and explains where drawtonomy can help.

What an HD map contains

A typical HD map encodes, at minimum:

Lane geometry — the precise centerline, left boundary, and right boundary of every drivable lane, usually as polylines or analytical curves.
Lane topology — how lanes connect: predecessor / successor relationships at intersections, lane changes, merges, splits.
Regulatory elements — traffic lights, traffic signs, stop lines, speed limits, right-of-way rules, crosswalks.
Static features — guardrails, road markings, lane types (bus, bike, parking), road surface attributes.
Reference frames — latitude / longitude / elevation, sometimes paired with a local coordinate system and a point cloud anchor.

The HD map is what lets a planner ask “what is the lane to my left”, a localiser correlate live sensor data against a known world, and a perception module bound its expectations of where signs and lights should be.

HD map vs SD map vs OpenStreetMap

The boundaries are fuzzy, but a useful rough split:

Layer	Accuracy	Lane semantics	Used by
SD (standard-definition) map	road-level	minimal	nav, route planning
OpenStreetMap	road-level, crowdsourced	optional tags	general purpose
HD map	centimetre-level	full lane / regulatory model	AV planning, prediction, localization

OpenStreetMap (OSM) acts as a substrate for some HD-map formats (notably Lanelet2, which is OSM-XML with extra tags) but raw OSM by itself is not an HD map.

Common HD map formats

The HD-map space has several active formats. The two that drawtonomy interacts with directly:

Lanelet2 — OSM-XML-based, developed at FZI, and the primary HD-map representation for Autoware. Geometry is polylines (linestrings); topology and regulatory elements are explicit relations.
OpenDRIVE — ASAM standard, analytical geometry (line, arc, spiral, polynomial), the de-facto HD-map format consumed by driving simulators (CARLA, esmini, IPG CarMaker, RoadRunner).

Other formats in active use include NDS (Navigation Data Standard), HERE HD Live Map, and various proprietary OEM formats. drawtonomy does not currently target those.

HD map authoring approaches

Producing an HD map at city scale is a survey-grade operation: mobile mapping vehicles, manual annotation pipelines, automated lane extraction from LiDAR / cameras, and human QA. Tools used in this space include:

TIER IV Vector Map Builder — browser-based Lanelet2 editor with full regulatory-element support.
JOSM with the Autoware Lanelet2 plugin — desktop OSM editor.
MathWorks RoadRunner — HD-map and scenario authoring used widely in industry.
Autocore MapToolbox — Unity plugin for Autoware Lanelet2 maps.

These are the tools to reach for when you need a survey-accurate HD map.

Where drawtonomy fits

drawtonomy is not an HD-map authoring tool in the survey-grade sense. It is a browser whiteboard tuned for driving scenarios. There are, however, a few narrow places where it sits alongside the real HD-map workflow:

HD-map sketches before authoring. If you’re scoping out a new intersection or a small road network and want a quick visual before you commit to JOSM or Vector Map Builder, drawtonomy can sketch lanes, intersections, and crosswalks in a few minutes.
Local edits to an existing Lanelet2 map. Drawtonomy can import a Lanelet2 OSM file, edit lane geometry visually, and export it back. Per the exporter implementation, regulatory elements are preserved round-trip via a sidecar but not yet editable in the UI — for that, Vector Map Builder or JOSM is the right tool.
Figures of HD-map concepts. Papers, slide decks, and design docs about HD-map work need clean illustrations of lanes, connections, and regulatory elements. drawtonomy is reasonable for the figure.
Small map → simulator pipeline. Drawtonomy can take a Lanelet2 sketch through OpenDRIVE 1.8 + OpenSCENARIO 1.3 to an esmini-ready zip. The export does not include junction <junction> elements or analytical clothoid geometry yet (see /explanation/exporter-architecture/), so this is suitable for small scenes rather than full HD maps.

For city-scale HD-map work, keep using the survey-grade tools. drawtonomy is the small browser canvas you reach for when you want a sketch, a figure, or a local fix.

In the same HD-map ecosystem

drawtonomy is a small contributor in an ecosystem with several established tools. The pages worth reading next: