CZML Structure

NOTE: This is a work in progress and reflects our plans NOT our current capabilities.

CZML is a subset of JSON, meaning that a valid CZML document is also a valid JSON document. Specifically, a CZML document contains a single JSON array where each object-literal element in the array is a CZML packet. A CZML packet describes the graphical properties for a single object in the scene, such as a single aircraft.

Note: we use javascript comments in these examples even though comments are not technically allowed in JSON.

[
    {
        // packet one
        "id": "PredatorUAV",
        // ...
    },
    {
        // packet one
        "id": "GroundControlStation"
        // ...
    }
]

Each packet has an id property identifying the object it is describing. IDs do not need to be GUIDs - URIs make good IDs - but they do need to uniquely identify a single object within a CZML source and any other CZML sources loaded into the same scope. We'll talk more about scopes later in this document.

If an id is not specified, the client will automatically generate a unique one. This prevents later packets from adding additional properties to the object. Also, other packets will not be able to reference the data in this one.

Properties

Packets describe graphical properties of their object. The following packet places a blue dot in Pennsylvania:

{
    "id": "GroundControlStation",
    "point": {
        "color": { "rgba": [0, 0, 255, 255] },
        "position": { "cartographicDegrees": [-75.0, 40.0, 0.0] }
    }
}

There are many standard properties, described on the CZML Content page.