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4 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
4.1 Actuator
A type of transducer that is a simple element that converts a signal to some action or real world phenomenon. In SensorML a actuator is a particular type of Process Model.
4.2 Coordinate Reference System CRS
A spatial or temporal framework within which a position andor time can be defined. According to ISO 19111, a coordinate system that is related to the real world by a datum.
4.3 Coordinate System CS
According to ISO19111, a set of mathematical rules for specifying how coordinates are assigned to points. In this document, a Coordinate System is extended to be defined as a set of
axes with which location and orientation can be defined. 4.4
Datum Undefined in ISO 19111. Defined here as a means of relating a coordinate system to the real
world by specifying the physical location of the coordinate system and the orientation of the axes relative to the physical object. For a geodetic datum, the definition also includes a reference
ellipsoid that approximate the surface of the planetary body. 4.5
Detector Atomic part of a composite Measurement System defining sampling and response characteristic
of a simple detection device. A detector has only one input and one output, both being scalar quantities. More complex Sensors, such as a frame camera, which are composed of multiple
detectors can be described as a detector group or array using a System or Sensor. In SensorML a detector is a particular type of Process Model.
4.6 Determinand
A Parameter or a characteristic of a phenomenon subject to observation. Synonym for observable.
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4.7 Location
A point or extent in space relative to a coordinate system. For point-based systems, this is typical expressed as a set of n-dimensional coordinates within the coordinate system. For bodies, this is
typically expressed by relating the translation of the origin of an object’s local coordinate system with respect to the origin of an external reference coordinate system.
4.8 Location Model
