Geospatial group OKs Web symbol mapping specs
- By Patrick Marshall
- Aug 17, 2007
The Open Geospatial Consortium has approved two new specifications aimed at standardizing the architecture of geospatial applications to ensure greater interoperability.
The Styled Layer Descriptor defines how user-defined symbolization of feature and coverage data work with Web map services. More specifically, the specification prescribes the manner in which users determine which features or layers are rendered with which colors or symbols.
The other specification'the Symbology Encoding Implementation Specification'defines Symbology Encoding, an XML language for styling information that can be applied to digital feature and coverage data. The specification merges two previous specifications and is independent of any service descriptions, meaning it could be used to describe styling information of systems not connected to any kind of service.
Taken together, the two specifications will enable developers to create symbol sets that can be accurately applied to Web maps regardless of their origin. \
'Say you've got wildfires in the West and they're bringing in firefighters from all over the country,' explained Sam Bacharach, executive director for outreach and community adoption at the Open Geospatial Consortium. 'But they bring in firefighters from Canada and from some of the states and now all of a sudden you've got people from a half-dozen different communities trying to fight the same fire. The problem is, only folks from one of those communities understand what the symbols mean. Everybody else has got to learn a new symbol set. Using this specification, each of them has the ability to have their map displayed in their own symbol set.'
According to Bacharach, the firefighter example isn't totally hypothetical. As it happens, federal agencies have already designed an emergency management symbol set using the specifications.
Patrick Marshall is a freelance technology writer for GCN.