Copyright © 2014 Open Geospatial Consortium
62
7.7 Requirement Class: Physical System Requirements Class
http:www.opengis.netspecsensorml2.0reqmodelphysical-system
Target Type Derived Encodings and Schema Dependency
http:www.opengis.netspecsensorml2.0reqphysical-component A physical system is used to model a hardware device as an aggregate process made of
one or more components and whose location in the real world is known and of importance.
Requirement
http:www.opengis.netspecsensorml2.0reqmodelphysical-systempackage-fully-implemented
Req 33. A schema or encoding definition supporting physical systems shall correctly implement all UML classes defined in the “PhysicalSystem” package described in
this section.
Sensor and actuator systems e.g. machines and robots are typically physical systems that perform a particular feat through the coordinated actions of both physical and non-
physical sub-processes. Even though a sensor system’s overall application is to sense something in the environment, the system itself can consist of sensing components e.g.
detectors and sensing subsystems, action e.g. actuators and robotic subsystems, and computational components.
Requirement
http:www.opengis.netspecsensorml2.0reqmodelphysical-systemdefinition
Example: A weather station is an example of physical system that is composed of several sensors thermometer, barometer,
wind sensor, etc. and other computational process such as an algorithm to compute wind chill. All these components can be described in SensorML and grouped in a PhysicalComponent description representing the
station as a whole. A hand-held digital camera can also be modeled as a physical system with an overall task of sensing radiance in a
scene and generating an image. However, the camera is an aggregate of various sub-processes, each of which can be physical or non-physical, and can be sensing, acting, or computational. For example, a light detector outputs a
measure of brightness, which serves as the input of a computational process which outputs a signal that provides input into an actuator that controls the opening or closing of the iris. The final iris size is sensed by another detector
which inputs that value into a process that encodes that value into an EXIF format that accompanies the image, which is generated by a entirely different subsystem of the camera.
SensorML OGC 12-000
Copyright © 2014 Open Geospatial Consortium
63
Req 34. A process shall be modeled as a “Physical System” if it provides a processing function with well‐defined inputs and outputs, if the device description is further
divided into subprocess components, and if knowledge of its physical location is of importance.
The model for PhysicalSystem, as shown in Fig. 7.18, is derived from AbstractPhysicalProcess, and adds the components and connections properties that have
been described in the non-physical counterpart, AggregateProcess Clause 7.4.
Figure 7.18 – Model for Physical Processing System
Copyright © 2014 Open Geospatial Consortium
64
Requirement
http:www.opengis.netspecsensorml2.0reqmodelphysical-systemdependency-core
Req 35. A schema or encoding passing the “Physical System” model conformance test class shall first pass the “Physical Component” conformance test class.
SensorML OGC 12-000
Copyright © 2014 Open Geospatial Consortium
65
7.8 Requirements Class: Processes with Advanced Data Types Requirements Class