GeoJSON to CoT (subflow)¶

Converts a GeoJSON Feature or FeatureCollection into TAK CoT XML. One message in → one message per feature out. Shipped as a Node-RED subflow so you can drop it into any flow that produces GeoJSON.

Used as a building block by every pipeline flow in the library (USGS, NOAA, ADS-B, Generic Sensor).

Import this subflow before importing any pipeline flow that uses it

Pipeline flows reference the subflow by id (subflow:geojson-to-cot). If you import a pipeline without the subflow present, the pipeline loads with an unresolved reference and won't deploy.

Input¶

msg.payload is any of:

A single GeoJSON Feature
A GeoJSON FeatureCollection
A plain array of Feature objects

Supported geometry.type: Point, Polygon, LineString. Other geometry types are dropped silently.

Output¶

One msg per feature on the single output wire:

msg.payload — CoT XML string, UTF-8, no trailing newline.
msg.topic — stable UID for the feature (for logging or routing).

Downstream nodes (tcp out, mqtt out, file out) receive each feature as its own message.

Environment variables¶

Name	Default	Purpose
`COT_TYPE`	`a-u-G`	CoT event type for Point features. Polygon/LineString features auto-switch to `u-d-f` (TAK freehand drawing) unless `COT_TYPE` already starts with `u-d`.
`UID_PREFIX`	`geojson`	Prefix for generated UIDs. Full UID is `<prefix>-<id>`, where `<id>` falls back to `feature.id`, `feature.properties.id`, or the feature's index.
`STALE_SECONDS`	`300`	How long each CoT event is valid. Set > poll interval so markers don't flicker.
`CALLSIGN_PROP`	`name`	`feature.properties.<this>` becomes the CoT `callsign` (TAK map label).
`REMARKS_PROP`	`description`	`feature.properties.<this>` becomes the CoT `<remarks>` (inspector text).
`ALTITUDE_PROP`	(empty)	Optional. If set, `feature.properties.<this>` becomes `point[@hae]`. If empty, uses `geometry.coordinates[2]` when present, else 0.
`SPEED_PROP`	(empty)	Optional. If set, adds a `<track>` element with this property's value as speed (meters/second).
`COURSE_PROP`	(empty)	Optional. If set, adds `course` to the `<track>` element (degrees true from north).

CoT output shape¶

Point features¶

<event version="2.0" uid="<prefix>-<id>" type="<COT_TYPE>" how="m-g" time="..." start="..." stale="...">
  <point lat="..." lon="..." hae="..." ce="9999999.0" le="9999999.0"/>
  <detail>
    <contact callsign="..."/>
    <track course="..." speed="..."/>   <!-- only if SPEED_PROP or COURSE_PROP set -->
    <remarks>...</remarks>
  </detail>
</event>

Polygon / LineString features¶

Outer ring vertices (Polygon) or line points (LineString) become <link> entries. Point position is the centroid. Interior rings (holes) are ignored — TAK CoT drawings don't represent them.

<event version="2.0" uid="<prefix>-<id>" type="u-d-f" how="m-g" time="..." start="..." stale="...">
  <point lat="<centroid-lat>" lon="<centroid-lon>" hae="0" ce="9999999.0" le="9999999.0"/>
  <detail>
    <link point="lat,lon,hae"/>   <!-- one per vertex -->
    <link point="lat,lon,hae"/>
    ...
    <strokeColor value="-65536"/>
    <strokeWeight value="2.0"/>
    <fillColor value="1073741824"/>
    <labels_on value="true"/>
    <contact callsign="..."/>
    <remarks>...</remarks>
  </detail>
</event>

To override the default stroke/fill colors, drop a change node after the subflow and edit msg.payload.

Typical wiring¶

[ http request ] → [ function: map to GeoJSON ] → [ GeoJSON → CoT ] → [ tcp out (TAK) ]

Every pipeline flow in the library follows this shape. See the Generic Sensor Feed for the smallest reference implementation.

Limitations¶

Polygon holes are ignored. TAK CoT drawings only model an outer ring.
MultiPoint, MultiPolygon, MultiLineString and GeometryCollection are dropped. Pre-process your GeoJSON to flatten them if you need per-part CoT output.
The subflow is stateless — it doesn't track which UIDs were emitted previously. If your source stops providing an entity, no CoT stale/delete event is sent; the marker expires via its STALE_SECONDS window.

Files¶

nodered/flows-library/subflows/geojson-to-cot.json — the subflow (importable from Import → Local → fasttak → subflows).