Various Symbology Best Practices are available for Law Enforcement and Public Safety (LEAPS) used in the context of Emergency Management. None of these best practices have been widely adopted, since in house-symbols are mostly preferred. In the case of a multi-institutional or internationalization the lack of a common set of symbology can be problematic.
The project OGC Testbed 11 had the target to advance a common set of symbology that can be used to share common operational pictures in an international environment.
The diagram summarizes the components involved in advancing the symbology work detailed in the requirements. A client interacts with an FPS (Feature Portrayal Server) to portray data from different sources using one common set of symbols. An SLD/SE producer is necessary to provide the client or FPS the symbology encoding. The SPARQL server provides the inference across features to get the best symbol for a particular feature type.
The SLD/SE Producer component has been implemented using the Web Processing Service (WPS) of Constellation-SDI. Processes have been implemented to support the following use case.
The SLDProducer component has the responsibility to provide an SLD instance to the client. The client shall provide two arguments: a community ID and a Feature Type. To allow chaining of processes, the SLDProducer has to return a raw SLD, not embedded in another response container. The WPS specification supports the RAWDATAOUPUT format which does not embed the result in a XML structure. Using this feature, the WPS call is integrated in the GetMap call for the SLDBODY attribute.
This project could demonstrate :
- The use ontology to represent symbols and portrayal rules for multiple communities
- Flexibility of FPS Service to render maps dynamically
- Importance of WPS service in SOA Architecture
- Openness of Constellation-SDI to provide OGC Services implementation.