| Term | Description |
|---|---|
| trajectory point | A spatio-temporal object that records a moving object's location and attributes at a single point in time. The location is expressed as 2D or 3D coordinates. Attributes can span multiple fields of different types. |
| trajectory object | A high-dimensional object built from a series of trajectory points and events. It encodes four dimensions of information: time, space, attributes, and events. See also: trajectory point, trajectory events. |
| trajectory timeline | The ordered sequence of time values in a trajectory object. |
| trajectory spatial | The spatial geometry of a trajectory object, represented as a linestring. |
| trajectory leaf | The spatial location of a moving object at a specific point in time — equivalent to a single trajectory point. See also: trajectory point. |
| trajectory attributes | The attribute values of a moving object across its trajectory points, such as velocity and direction. See also: trajectory attribute field. |
| trajectory attribute field | A named attribute of a trajectory object — for example, the velocity field. Each attribute field has exactly one value per trajectory point. See also: trajectory field value. |
| trajectory field value | The value of a trajectory attribute field at a given point in time. See also: trajectory attribute field. |
| trajectory events | Discrete events recorded along a trajectory — for example, refueling, breakdown, or car lock events in a vehicle trajectory. Each event consists of an event type ID and an event time. |
Figure 1. Trajectory object 