Volume 26 • No 02 • 2003
ISSN 0742-468X • Since 1978
On-line Since 2000
OGC Announces GML3
As noted in InfoNetrix’ (http://www.InfoNetrix.com) Market Horizons Report On Gis And Mobile Computing In The Electric Utility Industry (for more information read the excerpts in this issue), there are several converging forces that are dramatically impacting GIS technology. Chief among them is the use of the Web browser as a GIS platform. This is important because it allows GIS to use a much larger tool kit, and delivers GIS to the widest market at the lowest cost.
Nothing comes easy, though. While just about anyone can create a web site (gee, I did!), it takes a special skill to provide true GIS on the net. If the internet stands for anything it stands for standards and open technology. In the GIS arena, the Open GIS Consortium (OGC) — www.opengis.org — has made great strides in providing open standards. In fact, its very mission is “to deliver spatial interface specifications that are openly available for global use.”
Recently, the organization announced the approval and release of Geography Markup Language version 3.0 (GML 3). It defines a data encoding in XML that allows geographic data and its attributes to be moved between disparate systems with ease.
New additions in GML 3 include support for complex geometries, spatial and temporal reference systems, topology, units of measure, metadata, gridded data, and default styles for feature and coverage visualization. GML 3 is almost entirely backwards compatible with GML 2, so that developers and users familiar with GML 2 can begin working immediately with GML 3. Like GML 2, GML 3 will play a key role in both spatial data encoding and transport, and in the description of geographic objects for geospatial Web services.
According to Mark Reichardt executive director, Outreach and Community Adoption “The new release is modular, meaning that users can select out only the parts necessary for use, which simplifies and minimizes the size of implementations.”
Kurt Buehler, OGC CTO explains “GML 3’s modular structure means that those choosing to use GML can literally pick out the schemas or schema components that apply to their work. GML 3.0 also includes a sample packaging tool that creates a tailored schema containing only the required components from the GML core schemas.” Buehler also points out that it is OG ’s intention that this very broad specification, with more than 1000 new tags covering over 400 pages, remains relatively unchanged, save for minor bug fixes, over the next year or so. This stability will give potential implementers time to learn about and use GML 3 effectively.
Getting the specification
As with most specifications, there is lots of documentation, and only the serious GIS geek need bother to read them. But, if you are such a geek, click on over to http://www.opengis.org/techno/implementation.htm and start downloading.
About OGC
OGC is an international industry consortium of more than 240 companies, government agencies and universities participating in a consensus process to develop publicly available interface specifications. OpenGIS® Specifications support interoperable solutions that “geo–enable” the Web, wireless and location–based services, and mainstream IT. The specifications empower technology developers to make complex spatial information and services accessible and useful with all kinds of applications. Visit the OGC website at www.opengis.org.
| 
