International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
an example is shown in Figure 9. After a subscription has been
submitted successfully, the service starts processing.
Subscription
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mins: fas: http: //wws.opengis.net/fes /2.0
»mins:gml:http: //www.opengis.net /gml /3.2
»amins:ows:http: //www.opengis.net /ows
»amins:xsi:http: //wwuw.w3.org /2001/XMLSchema instance
towmins:swe:http: //www.opengis.net /swe /1.0. 1
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=fes:and 3 Ÿ
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Figure 9. Example for a subscription document in a tree
representation.
The final web client allows visualizing the events that have
been cached by the SES client (Figure 10). If an event message
was received by the SES client, the web client can be used to
evaluate in detail the situation that led to the alert. The web
client shows a list with an overview of all events that occurred.
A single list item can be expanded to give a detailed description
of the event. In addition, the corresponding history of
measurements can be visualized using the plotting functionality
of the client.
Figure 10. Extended Web client and SES-Client.
6. RELATED WORK
In the last few years, several projects started that use SOS
services for early-warnings systems in respect to flooding. One
prominent example is the Tsunami Service Bus of the German
Indonesian Tsunami Early Warning System (GITEWS)
(Fleischer et al., 2010) which uses SOS, the Sensor Planning
Service (SPS), SAS and the Web Notification Service (WNS).
Other projects related to flooding observe water gauges or
groundwater levels, e.g., by the Wupperverband SWE project
(Spies & Heier, 2008) or within the Dutch spatial data
infrastructure (Jellema & Gijsbers, 2008). None of those
projects focuses on carly flood warnings based on soil moisture
profiles.
Like GITEWS, other SWE early-warning systems often use the
combination of SOS, SPN, SAS and WNS. A typical example is
the European project OSIRIS (OSIRIS Consortium, 2009) that
developed an open architecture for smart and interoperable
networks in risk management based on in-situ sensors and
demonstrated the deficiencies of SAS/WPN. Experiences with
the SES are rare; for an overview see (Bróring et al., 2011).
Similarities with WEBBOS in objective and services used has
CSIRO's *South Esk Hydrological Sensor Web", which
monitors the water cycle in Tasmania and particular forecasts
the short-term river flow (Guru et al., 2008).
Since version 2.9, OpenLayers also provides a native SOS
support (http://dev.openlayers.org/docs/files/OpenLayers/
Protocol/SOS/v! 0 0-js.html). However, its functionality is
rather restricted. For example, a request of sensor observations
over time periods is not supported. Other SWE client projects
can be found at http://52north.org/communitics/sensorweb/
7. CONCLUSIONS
In this paper, we presented the results of the WEBBOS project.
The objective of WEBBOS has been to build up a system for
carly flood warnings by measuring soil moisture profiles. We
have shown that current SWE services in combination with
existing SWE and mapping libraries allow building up a
suitable software framework for a web-based sensor system in
this application field. The main contributions are:
e the incorporation of soil moisture profiles into the SWE
data model,
e the integration of the new OGC Sensor Event Service, and
e the development of a flexible web client for mapping and
visualization of the service results including SWE events.
As next step, it is planned to use the WEBBOS system for other
types of environmental monitoring, e.g., in the context of
coastal protection. Furthermore, it is intended to integrate data
stream management systems (Babcock et al., 2002) with their
powerful capabilities for complex event processing (CEP) and
processing of very large data streams.
8. REFERENCES
Annoni, A. et al., 2005. Orchestra: Developing a Unified Open
Architecture for Risk Management Applications. In: Oosterort,
P. van, Zlatanova, S., Fendel, E.M. (eds.): Geo-information for
Disaster Management, Springer, pp. 1-17.
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