Semantic Sensor Web

(Geospatial Semantics)

ANUSURIYA DEVARAJUInstitute for Geoinformatics,

University of MuensterUniversity of Muenster.([email protected])

Definitions : Sensor Web (OGC, NASA)OGC Sensor Web Enablement (SWE)( )SWE SpecificationsHow SWE Works? An Example…Semantic Sensor Web & Motivating ExampleArchitectureApproachApproach– Semantic Annotation– Ontologies (Sensors, Observations, Space, Time, Domain-specific)– Rules-based Reasoning– Rules-based Reasoning

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A Sensor Web consists of intra-communicating, spatially-distributed sensor pods that are deployed to monitor and explore environments [NASA New Technology Report on Sensor Webs]

Information sharing among

Intelligent autonomous ti ( d t d t)

the pods

operations (adapt and react)

3Source: Delin K and Jackson S, (2001) , The Sensor Web: A New Instrument Concept

Sensor Web refers to web accessible sensor networks and archived sensor data that can be discovered and accessed using standard protocols and application program interfaces [Botts et al. , 2006]

4Source: M. Botts, G. Percival, C. Reed, J. Davidson (2006) , OGC SWE : Overview and High Level Architecture

Sensor Web concept (OGC, 2006)

Sensors and sensor observations will be web accessible and discoverable through standardized web servicesSensors will be self-describing to humans and software using standard encodingsMost sensor observations will be easily accessible in near realMost sensor observations will be easily accessible in near real time over the webReal-time mining of observations to find phenomena of immediate i t tinterestSensor systems will be capable of issuing alerts based on observations, as well as be able to respond to alerts issued by other sensors

5Source: M.Botts and Robin A, (2007), Bringing the Sensor Web Together

Software will be capable of on-demand geo-location and processing of observations from a newly-discovered sensor without a priori knowledge of that sensor systemSensors, simulations, and models will be capable of being configured and tasked through standard, common web interfacesconfigured and tasked through standard, common web interfacesThe semantics of sensor web components will be tied to well-defined ontologies that will allow better understanding of potential relationships between systemsrelationships between systems

6Source: M.Botts and Robin A, (2007), Bringing the Sensor Web Together

The role of Sensor Web Enablement for supporting heterogeneous sensors, models, simulations, and decision support tools.

Enable interoperability between disparate sensor

types disciplines andtypes, disciplines, and agencies.

Leverage benefits of open d dstandards

Service Oriented Architecture (SOA) based( )

Virtually any sensor or modeling system can be

supported

7Source: M.Botts (2008), OGC Sensor Web Enablement (Intro) - Presentation Slides

supported

Information Encodings

Observations & Measurements (O&M) : The general models and XML– Observations & Measurements (O&M) : The general models and XML encodings for observations and measurements.

– Sensor Model Language (SensorML) : Standard models and XML Schema for describing the processes within sensor and observation processingfor describing the processes within sensor and observation processing systems.

– Transducer Markup Language (TML) : Conceptual model and XML encoding for supporting real-time streaming observations and tasking commands from and to sensor systems.


9Source: https://wiki.52north.org/bin/view/Sensornet/SosDataModeling

Web Services

Sensor Observation Service: Access Observations for a sensor or sensor– Sensor Observation Service: Access Observations for a sensor or sensor constellation, and optionally, the associated sensor and platform data

– Sensor Alert Service : Subscribe to alerts based upon sensor observations– Sensor Planning Service : Request collection feasibility and task sensor– Sensor Planning Service : Request collection feasibility and task sensor

system for desired observations– Web Notification Service : Manage message dialogue between client and

Web service(s) for long duration (asynchronous) processes( ) g ( y )– Sensor and Observation Registry : Common interface for discovery of

sensor systems, processes, models, and observations


(Sensor Observation Service Concept)

11Source: http://www.sensorsportal.com/HTML/DIGEST/september_06/P_84.pdf

( p )

12Source: http://www.sany-ip.eu/book/export/html/2855

13Source: http://v-swe.uni-muenster.de:8080/WeatherSOS/



16Images : (a) http://esto.nasa.gov/info_technologies_SensorWeb.html (b) http://www.flickr.com/photos/dullhunk/3448804778/

SWE specifications enables a wider access to sensors and observations. Nevertheless, an effort is required to collate and i t t thinterpret them..

DPIPWE

Observation Archives

Stream C t

HydroTas

DPIPWE FlowXMLXML

WaterCourse

Current stream flow data at river

X?

WDSWaterCourse

DischargeXMLXML

Stream

Sensor Collection ServiceSWE Client

StreamDischarge

XMLXML

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Sensor Collection Service

A framework that extends SWE and Semantic Web technologies to provide enhanced meaning to sensor data– How? Annotate sensor data with spatial, temporal and thematic semantic

metadata

18Source: Sheth A and Henson C, 2008, Semantic Sensor Web



Embedding semantics in an XML document using RDFa

<swe:component rdfa:about=“time_1” rdfa:instanceof=”time:Instant”><swe:Time rdfa:property=“xs:date-time”>20080308T05:00:00 </ Ti ></swe:Time></swe:component>

(a timestamp encoded in O&M and semantically annotated with RDFa)

time 1 time:Instant

rdf:type

time_1

20080308T05:00:00xs:date-time


Creating internal and external links within XML documents using XLink (XML Linking Language)

(Semantic annotation of O&M with XLink)

22Source: http://geostandards.geonovum.nl/index.php/5.3.2_O%26M

Sensor and Sensing Procedure : W3C SSN Incubator, NIST Sensor Standards Harmonization, OntoSensor, CESN ontology, SWAMO, ….Observation : O&M ontology, Functional Ontology of O&M…gy, gyUnits of Measurements : UCUM Units, SWEET Units, QUDT, …Spatial : GML Ontology..Temporal: W3C Time Ontology, p gy,Valid-Time Temporal Ontology..Sensed domain (thematic) : *Domain- specific ontologiesp g

23Image: Sheth A and Henson C, 2008, Semantic Sensor Web

Point measurements performed by an instrument (e.g., evaporation pan)

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The partial view of the Sensor Network Ontology (SNO)

Source: Devaraju A, et al. (2010), Combining Process and Sensor Ontologies to Support Geo-Sensor Data Retrieval

Incorporates rules into an ontology schema to derive additional knowledge from semantically annotated sensor data

[Environment Canada] A blizzard must have winds of 40 km/h or more,have snow or blowing snow, visibility less than 1 km and a windchill of lessthan 25 degrees celsius All of these conditions must last for 4 hours or more

WindSpeed(a) ≥ 40km/h Duration(a) ≥ 4hours Visibility(b) ≤ 1km Duration(b) ≥ 4hours

than -25 degrees celsius. All of these conditions must last for 4 hours or more.

Visibility(b) ≤ 1km Duration(b) ≥ 4hours WindChill(c) < -25◦C Duration(c) ≥ 4hours → Blizzard(x)

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Education

Semantic Sensor Web