DHS Promotes Open Geospatial Data Standards

Emergency managers and first responders from diverse organizations need to share geospatial data so they are working from a "Common Operational Picture" during emergencies. Doing so has become much easier as a growing platform of standards now enables Web-based systems to work together.

Standards from the Open Geospatial Consortium (OGC) and the International Organization for Standardization make it much easier for solution providers to build open systems that integrate with other solution providers.

The U.S. Department of Homeland Security (DHS), through its business practices and geospatial enterprise architecture, recognizes the OGC's value, and encourages consensus standards and specifications.

Particularly in emergency response, it's important to reduce map-reading errors, which means presenting information in symbols familiar to users.

In August 2007, OGC members approved an XML-based standard that enables solutions that tailor data "on the fly" with presentation styles familiar to specific user communities, regardless of the data source. The OpenGIS Symbology Encoding specification and related OpenGIS Styled Layer Descriptor (SLD) specification meet the needs of diverse emergency response teams who share diverse data sources, but require conformity to map styles designed for particular jobs.

In the past, it was necessary for all users in a community to have the same software running on the same hardware to make identical displays of the same data. Using open standards, critical-data providers and users in a city or region can get the same results without having the same software or hardware - the same data is the key to a common display. The world's vendors have now outfitted their software with open interfaces and the ability to display open-symbol sets, letting each location use whatever software best suits its needs.

The SLD standard has potential to further the DHS's data-sharing goals by portraying an operational picture that is common to all users. The standard could enable developers to adapt applications to accommodate visually impaired - particularly colorblind - individuals.

As municipalities, states, regional authorities and federal agencies contract GIS development for emergency and nonemergency uses, they increasingly will include standards requirements that match those of both the DHS and their other GIS sharing partners.

Defining styling rules requires a styling language the client and server can both understand. The Symbology Encoding specification provides this language; it is an XML language for styling information that can be applied to digital feature data (vectors, essentially) and coverage data (gridded data). It allows users to determine which colors or symbols are used to render features or layers.

Symbology Encoding is independent of service descriptions, such as Web services, and could therefore be used to describe styling in systems not connected to a service, such as desktop GIS.

It is important that information system solution providers use the new open standards. This allows data to be presented to user communities in a familiar language, regardless of the data's source, enabling first responders and emergency managers from diverse organizations to understand each other.

Sam Bacharach is the executive director of outreach for the Open Geospatial Consortium, an international industry group of 350 companies, government agencies and universities participating in a consensus process to develop publicly available interface specifications.