import/parseBaseMap

Decodes a base_map.bin binary buffer and restores it as editor GeoJSON state.

parseBaseMap

async function parseBaseMap(buffer: Uint8Array): Promise<ParsedMapState>

Parameters

Name	Type	Description
buffer	Uint8Array	Raw bytes of a base_map.bin file

Returns

interface ParsedMapState {
  project: ProjectConfig
  lanes: LaneFeature[]
  junctions: JunctionFeature[]
  signals: SignalFeature[]
  stopSigns: StopSignFeature[]
  crosswalks: CrosswalkFeature[]
  clearAreas: ClearAreaFeature[]
  speedBumps: SpeedBumpFeature[]
  parkingSpaces: ParkingSpaceFeature[]
  roads: RoadDefinition[]
}

Steps

1. decodeMap(buffer) — binary → ApolloMap JS object
2. Extract originLat / originLon from map.header.projection.proj
3. setGlobalProjection(originLat, originLon)
4. For each ApolloLane:
   • Convert central_curve PointENU → WGS84 LineString
   • Estimate width from left_sample + right_sample averages
   • Extract boundary types from left_boundary.boundary_type[0].types[0]
   • Restore topology IDs from predecessor_id, successor_id, etc.
5. For each polygon element (junction, crosswalk, clear area, parking space):
   • Convert polygon.point[] PointENU → WGS84 Polygon
6. For each line element (stop sign, speed bump):
   • Convert stop_line[0] or position[0] curve → WGS84 LineString
7. For each signal:
   • Convert stop line → WGS84 LineString
   • Derive position from stop line midpoint

Example

const buffer = new Uint8Array(await file.arrayBuffer())
const parsed = await parseBaseMap(buffer)

useMapStore.getState().setProject(parsed.project)
useMapStore.getState().loadState({
  lanes: Object.fromEntries(parsed.lanes.map((l) => [l.id, l])),
  // ...
})

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parseProjString (internal)

function parseProjString(projStr: string): { lat: number; lon: number } | null

Extracts +lat_0 and +lon_0 values from a proj4 string using regex. Returns null if the string is absent or malformed.

---

Width estimation

const widthSamples = lane.leftSample.map((s, i) => {
  const rightS = lane.rightSample[i]
  return s.width + (rightS?.width ?? s.width)
})
const width = mean(widthSamples) || 3.75

This produces a single uniform width value, which is acceptable for lanes with approximately constant width.

---

Header bytes decoding

Proto Header fields version, date, district, and vendor are bytes type. The bytesToString() helper decodes them from base64 (protobufjs toObject output) or Uint8Array back to UTF-8 strings.

Known limitations

• overlap_id arrays are not restored (recomputed on next export)
• Signal subsignal geometry is not restored
• z coordinates are discarded (editor is 2D)