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kring edited this page May 2, 2012 · 28 revisions

This page describes the possible content of a CZML document or stream. Please read CZML Structure for an explanation of how a CZML document is put together.

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

Position

Specifies the position of the object in the world. The position has no direct visual representation, but it is used to locate billboards, labels, and other primitives attached to the object.

Property Name: position

Interpolatable: yes

Sub-properties:

Name Scope JSON Description
referenceFrame Interval string The reference frame in which cartesian positions are specified. Possible values are FIXED and INERTIAL. This property is ignored when specifying position with any type other than cartesian. If this property is not specified, the default reference frame is FIXED.
epoch Packet string The epoch (time 0.0), specified as an ISO 8601 date and time string, for times specified in epoch seconds. This property is required if a sample time or other property is specified in epoch seconds. It is ignored if this property is not defined by samples for this interval.
nextTime Packet string or number The time of the next sample within this interval, specified as either an ISO 8601 date and time string or as seconds since epoch. This property is used to determine if there is a gap between samples specified in different packets.
previousTime Packet string or number The time of the previous sample within this interval, specified as either an ISO 8601 date and time string or as seconds since epoch. This property is used to determine if there is a gap between samples specified in different packets.
cartesian Interval array The position specified as a Cartesian [X, Y, Z] position in the meters relative to the referenceFrame. If the array has three elements, the position is constant. If it has four or more elements, they are time-tagged samples arranged as [Time, X, Y, Z, Time, X, Y, Z, Time, X, Y, Z, ...], where Time is an ISO 8601 date and time string or seconds since epoch.
cartographicRadians Interval array The position specified as a WGS 84 Cartographic [Longitude, Latitude, Height] where longitude and latitude are in radians and height is in meters. If the array has three elements, the position is constant. If it has four or more elements, they are time-tagged samples arranged as [Time, Longitude, Latitude, Height, Time, Longitude, Latitude, Height, ...], where Time is an ISO 8601 date and time string or seconds since epoch.
cartographicDegrees Interval array The position specified as a WGS 84 Cartographic [Longitude, Latitude, Height] where longitude and latitude are in degrees and height is in meters. If the array has three elements, the position is constant. If it has four or more elements, they are time-tagged samples arranged as [Time, Longitude, Latitude, Height, Time, Longitude, Latitude, Height, ...], where Time is an ISO 8601 date and time string or seconds since epoch.
interpolationAlgorithm Interval string The algorithm to use for interpolation. Possible values are LAGRANGE, HERMITE, or GEODESIC. The default is LAGRANGE. If the position is not sampled over this interval, this property is ignored.
interpolationDegree Interval number The degree of the polynomial to use for interpolation. The default value is 1 meaning linear interpolation. The value of this property is ignored for GEODESIC interpolation.

Examples:

{
  "id": "MyObject",
  "position": { "cartographicDegrees": [-75.0, 40.0, 0.0] }
}
{
  "id": "InternationalSpaceStation",
  "position": {
    "referenceFrame": "INERTIAL",
    "epoch": "2012-05-02T12:00:00Z",
    "cartesian": [
      0.0, -6668447.2211117, 1201886.45913705, 146789.427467256,
      60.0, -6711432.84684144, 919677.673492462, -214047.552431458,
      90.0, -6721319.92231553, 776899.784034099, -394198.837519575,
      150.0, -6717826.447064, 488820.628328182, -752924.980158179,
      180.0, -6704450.41462847, 343851.784836767, -931084.800346031,
      240.0, -6654518.44949696, 52891.726433174, -1283967.69137678,
    ],
    "nextTime", 300.0,
    "interpolationAlgorithm", "LAGRANGE",
    "interpolationDegree", 5
  }
}

Vertex Positions

Specifies the world-space positions of vertices. The vertex positions have no direct visual representation, but they are used to define polygons and polylines attached to the object.

Orientation

Specifies the orientation of the object in the world. The orientation has no direct visual representation, but it is used to orient models, cones, and pyramids attached to the object.

Billboard

Defines a billboard, or viewport-aligned image. The billboard is positioned in the scene by the position property. A billboard is sometimes called a marker.

Point

Defines a point, or viewport-aligned circle. The point is positioned in the scene by the position property.

Label

Defines a string of text. The label is positioned in the scene by the position property.

Polyline

Defines a polyline, which is a line in the scene composed of multiple segments. The vertices of the polyline are specified by the vertexPositions property.

Path

Defines a path, which is a polyline defined by the motion of an object over time. The possible vertices of the path are specified by the position property.

Polygon

Defines a polygon, which is a closed figure on the surface of the Earth. The vertices of the polygon are specified by the vertexPositions property.

Cone

Defines a cone. A cone starts at a point or apex and extends in a circle of directions which all have the same angular separation from the Z-axis of the object to which the cone is attached. The cone may be capped at a radial limit, it may have an inner hole, and it may be only a part of a complete cone defined by clock angle limits. The apex point of the cone is defined by the position property and extends in the direction of the Z-axis as defined by the orientation property.

Pyramid

Defines a pyramid. A pyramid starts at a point or apex and extends in a specified list of directions from the apex. Each pair of directions forms a face of the pyramid. The pyramid may be capped at a radial limit.

Imagery

Defines imagery to be drawn on the surface of the Earth.

Layers

Layers define the hierarchical relationship among objects.

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