Satellite imaging systems, meteorological stations, stream gauges, SCADA, air quality stations, and security cameras are all types of sensor systems.Emergency response services, homeland security, and many other applications have a very real need to be able to access these sensor systems in real time and to integrate or fuse these sensor inputs with other geospatial data and geoprocessing services. Therefore, it is important to be able to control remote sensors and to obtain data from them, and to be able to aggregate data from multiple sensors and to integrate that with data from other kinds of sensors or with other geospatial data.
These capabilities have in the past been the stuff of the arcane domain of telemetry.But like most information technologies, telemetry is rapidly advancing from idiosyncratic, stovepiped, non-interoperable systems into a world of standards-based systems that work together. Because sensor location and orientation are often important, we might expect that the world of sensor standards would intersect OGC's world of geospatial standards, and it has.
An increasing number of sensors are location enabled and can be accessed via radio, LAN, WiFi, or other technology.These sensors typically provide time, date, and location stamps along with the observation data the sensor is designed to collect.
For many organizations and many applications, it makes sense to use Internet and Web protocols to communicate with the sensors.Structured text schemas conforming to the Web's eXtensible Markup Language (XML) can be used to publish formal descriptions of the sensor's capabilities, location, and interfaces.Web brokers, clients and servers can then parse and interpret XML data, enabling automated Web-based discovery of the existence of sensors and evaluation of their characteristics based on their published descriptions.Information provided in the XML schema about a sensor's control interface enables communication with the sensor system: to determine, for example, its state and location; to issue commands to the sensor or its platform; and to access its stored or real-time data.XML thus supports mechanisms for Web-based discovery of a sensor and Web-based access to its capabilities.This approach to sensor description also provides a convenient way to automatically generate comprehensive standard-schema metadata for data produced by sensors, facilitating the discovery and interpretation of data in distributed archives.
To maximize the discoverability, interoperability and system integration benefits of XML-based metadata for sensors and sensor-derived data, the OGC is developing and promoting a standard sensor description model within its Sensor Web Enablement (SWE) effort. The Sensor Model Language (SensorML), which got its start in earlier NASA funded projects, provides an XML schema for defining the geometric, dynamic, and observational characteristics of sensors.SWE goes beyond sensor models to provide a standard XML encoding scheme for observations and measurements of all kinds.And it is yielding specifications for open interfaces for:
- Sensor Collection Service - a software service that provides observed values by seeing what sensors of a specified type are available in a specified region.
- Sensor Planning Service - a software service that enables acquisition requests and notification of relevant events
- Sensor Registries - a catalog that enables discovery of sensors and observed values.
ORNL is bringing important requirements into the OGC SWE program and helping to mature the OGC SWE specifications.As part of this function, for instance, ORNL is serving as the catalyst for the complementary blending of SensorML and the IEEE 1451 standard for "plug-n-play" sensors, as well as helping mature the Sensor Alert Service through the use of existing standards, such as the OASIS Common Alert Protocol (CAP).
Other OGC members, too, want to move SWE forward.SWE will be important thread in the upcoming OWS-3 Interoperability Initiative, an OGC testbed that will bring together a team of sponsors and participants to advance OpenGIS Specifications in a hands-on prototyping and testing activity.
Underlining the significance of SWE, OGC's third annual Emerging Technology Summit (ETS III) is titled "Advancing the Sensor Web." The two day event is organized by OGC, the Geospatial Information and Technology Association (GITA) and the Oak Ridge National Laboratory SensorNET Program.It will be held April 14-15, 2005 at the Washington Hilton Hotel in Washington, DC.Registrants already include representatives of a wide variety of sensor web stakeholder communities: Homeland Security, meteorology, oceanography, environmental management, transportation, defense, logistics and others.Watch OGC's web site for information about the program, including exciting keynote speakers.We hope to see you there!