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Converter Pipeline

The converter transforms an osi3.MapAsamOpenDrive message into a Foxglove SceneUpdate in four stages.

Stage 1: Message Deserialization​

File: src/utils/proto.ts

The incoming MCAP message is interpreted as:

  • map_reference — stable identifier for cache keys
  • open_drive_xml_content — embedded OpenDRIVE XML string

The converter uses the XML payload directly; there is no intermediate TypeScript road-model parser.

Stage 2: WASM Processing​

Files: src/wasm/index.ts, src/converters/openDriveMap/sceneUpdateConverter.ts

sceneUpdateConverter.ts eagerly loads libOpenDRIVE at registration time and calls:

  1. createFromXml(xml, ...)
  2. get_road_network_mesh(eps)

libOpenDRIVE performs:

  • OpenDRIVE XML parsing
  • reference-line geometry evaluation
  • elevation, superelevation, crossfall, and lane offset application
  • lane, road marking, road object, and road signal mesh generation

The result is a RoadNetworkMesh containing feature-specific mesh chunks plus outline data.

Stage 3: Schema Adaptation​

File: src/converters/openDriveMap/sceneUpdateConverter.ts

The TypeScript adapter converts WASM output into Foxglove primitives:

  • lane meshes → TriangleListPrimitive
  • lane outline indices → LinePrimitive
  • road marking meshes → TriangleListPrimitive
  • road object meshes → TriangleListPrimitive
  • road signal meshes → TriangleListPrimitive

Feature-specific builders group mesh chunks into SceneEntity objects with stable IDs, metadata, frame_id="global", and persistent lifetimes.

When panel settings change, the converter emits SceneEntityDeletionType.ALL before returning the newly selected layers.

Stage 4: Caching​

File: src/converters/openDriveMap/context.ts

Generated entities are cached by:

  • map_reference
  • serialized panel settings hash

If both values match the previous invocation, the converter returns the cached SceneEntity[] without re-running libOpenDRIVE.

End-to-End Summary​

MapAsamOpenDrive
  → extract open_drive_xml_content
  → createFromXml()
  → get_road_network_mesh(eps)
  → build SceneEntity layers
  → cache by map_reference + settings hash
  → return SceneUpdate