cesiumgs/cesiumjs-ai-starter-app/czml-custom-properties

CZML Custom Properties

• "properties": { "<propertyName>": { "number": <value> } } — a top-level packet property (a

sibling of "position"/"polygon"/etc., not nested inside a graphics property) holding arbitrary named data on an entity. Wrap the value by its type: { "number": <value> } for numeric data, { "string": "<value>" } for text, { "boolean": true|false } for flags.

• For a value that changes over time, use either:
• The same "epoch" + interleaved-timestamp-and-value pattern as any other sampled property:

{ "epoch": "<ISO8601>", "population": [t0, v0, t1, v1, ...] }, or

• An array of interval-scoped values, each with its own "interval":

"population": [{ "interval": "<ISO8601 start>/<ISO8601 end>", "number": 1000 }, { "interval": "<next start>/<next end>", "number": 2000 }]. This same interval-array pattern also works for any other property (e.g. "position") when an entity's full timeline needs to be built incrementally from several non-overlapping segments, as if streamed across separate CZML packets.

Example: a time-varying custom property alongside a polygon entity

[
  { "id": "document", "name": "Custom properties", "version": "1.0" },
  {
    "id": "region-1",
    "properties": {
      "epoch": "2026-01-01T00:00:00Z",
      "population": [0, 10000, 3600, 12000, 7200, 15000]
    },
    "polygon": {
      "positions": {
        "cartographicDegrees": [-90, 30, 0, -89.9, 30, 0, -89.9, 30.1, 0, -90, 30.1, 0]
      },
      "extrudedHeight": 15000,
      "material": { "solidColor": { "color": { "rgba": [0, 128, 255, 150] } } }
    }
  }
]