Vol.34 No.1 February 2000
Work With the SEDRIS Organization Begins
George S. Carson
This edition of the Standards Pipeline reports on new work in JTC 1/ SC 24 (Computer Graphics and Image Processing) in the area of synthetic environments. The last Standards Pipeline described how at SC 24’s Synthetic Environments Study Group met in the Republic of Korea in June 1999 and recommended that work should proceed to prepare for development of an international standard in cooperation with the SEDRIS Organization. As a result, SC 24 called an organizational meeting for October 1-4, 1999 in Alexandria, VA, to form a new working group and begin the development of this standard. In addition, a series of other meetings have been held to discuss coordination of spatial standardization among the many interested parties, including JTC 1, ISO TC 211, the SEDRIS Organization and the Open GIS Consortium.
SC 24/WG 8 Meeting Report
Twenty-one delegates from four countries and the SEDRIS Organization attended the organizational meeting for SC 24/WG 8 in Alexandria, VA. The attendees agreed to form a new WG 8 within SC 24 with the following scope of work:
The working group then determined that the best initial "packaging" of SEDRIS technology as international standards would be as four different standards:
Four new work item proposals were created (documents WG 8 N0009 – WG 8 N0012) as well as a supporting document (WG 8 N 0008) and were forwarded to JTC 1 for approval. In addition, a cooperative agreement (WG 8 N0007) between ISO/IEC and the SEDRIS Organization was finalized and signed by representatives of each organization. Future WG 8 meetings are scheduled for: January 17-21, 2000 in Orlando, FL, U.S.A.; April 6-8, 10, 2000 in The Hague, Netherlands; and July 2000 with the SC 24 plenary and WG meetings in France.
For more information about the work of SC 24/WG 8 as well as copies of all WG 8 documents mentioned above, see the website.
Special OGC Meeting
A spatial standards briefing was held on December 9, 1999 on the campus of UCLA in Los Angeles, CA in conjunction with a plenary meeting of the Open GIS Consortium (OGC). The session was informal and directed at providing background information to help OGC come to a consensus position on issues regarding placement and coordination of formal standards activities in the area of spatial information standards.
Cliff Kottman, VP and Chief Scientist of the Open GIS Consortium, opened the meeting with a short briefing to acquaint OGC members with the issues. Following Cliff’s introduction, additional presenters included:
Data Management and Services)
The presentations made at this meeting provide a good picture of spatial standardization and are posted at the web.
Meeting on Spatial Standardization
On December 17, 1999 an informal meeting on spatial standardization was held at Defense Information System Agency (DISA) in Reston, VA. Twenty experts who are participants in various standards activities participated in this meeting. The major presentations covered the work of ISO TC 211, OGC, JTC 1/SC 24 and the SEDRIS Organization. The presentations are posted ont the website.
Introduction to SEDRIS
The next section provides SEDRIS background information prepared by Farid Mamaghani for circulation to attendees at the December OGC meeting.
Environmental data is an integral part of many of today’s information technology applications. The use of environmental data will grow substantially as availability and access to such data increases and as tools for manipulation of environmental data become less expensive and more sophisticated.
As this trend continues, the representation and sharing of environmental data will play a key role in the interoperation of heterogeneous systems and applications that use such data. This need was recognized in the mid-’80s, when the ability to network large numbers of heterogeneous simulation systems became a practical reality. Research and work in this area continued while a better and more complete understanding of the complex issues associated with describing and sharing of environmental data for a wide variety (simulation) applications was formed. In 1994, the Synthetic Environment Data Representation and Interchange Specification (SEDRIS) was conceived in order to tackle these issues in a uniform and unified manner.
Although the initial application domain for SEDRIS stems from the needs of the modeling and simulation field, it was immediately recognized that the representational technologies required to capture and communicate environmental data are fundamentally one and the same, and, in large part, can be dealt with independent of the end applications. At the same time, it was also understood that too often end applications shape and form the characteristics of how data and data representation are used. The challenge for SEDRIS, then, was to provide a means for representation and sharing of environmental data that not only was efficient in practical use, but also was specific enough to address the real needs of a wide variety of end applications while preserving the degree of semantics that is needed for others to understand the nature of the data. The range of end applications included representation of environmental data for applications such as analysis, visualization, simulation, planning, modeling, etc. This took into account the meteorological and oceanographic communities, the simulation sector (both military and commercial), the GIS (or more broadly the environmental information systems) community and the military operational community (i.e. C4I), as well as others that needed to share or communicate environmental data.
Added to this was the goal of getting away from stove-pipe views of the environment, and providing a mechanism that also allowed for integrated environmental data to be represented. Integrated environmental data, where ocean, terrain, atmosphere and space data (about a region) can be seamlessly represented, was recognized as a key aspect of many future information technology applications. And although very few applications today deal with such diverse data at the same time, developers of SEDRIS believed such a need would be reality in the future.
With these objectives and challenges in mind, SEDRIS was initiated in 1994, and has been conducted as an open project with the objective of solving these challenges in practical ways that can be immediately used by both data providers and consumers, while at the same time leveraging and taking advantage of existing standards whenever possible.
SEDRIS is fundamentally about two aspects: (1) representation of environmental data and (2) the interchange of environmental data sets.
To achieve the objectives of representation and interchange of environmental data, we rely on five core SEDRIS technology components: the SEDRIS Data Representation Model (SDRM), the Environmental Data Coding Specification (EDCS, previously called SDCS), the Spatial Reference Model (SRM), the SEDRIS interface specification (API) and the SEDRIS Transmittal Format (STF).
Three of the core technology components of SEDRIS (SDRM, EDCS and SRM) are used to achieve the first aspect of SEDRIS.
Through the use of the data representation model one can describe and articulate one’s environmental data clearly, while at the same time using the same representation model to understand others’ data unambiguously. The SDRM is based on an object-oriented data representation model that provides not only a clear description of data from all environmental domains - space, atmosphere, terrain and ocean - through a single schema, but also includes the logical relationships between the data elements. This allows for polymorphic representation of the same data, while also ensuring semantics of the data are correctly understood by users.
The environmental data coding specification (EDCS) provides the means for classification (naming, labeling, identification) of environmental objects as well as articulating their attributes (characteristics) based on a known and agreed upon convention. The foundation of this convention is built upon the FACC standard. Since the nature and the types of data SEDRIS needs to represent is broader than the cartographic domain, the FACC foundation was expanded both in breadth and depth to allow for additional (new) codes, as well as inclusion of the ocean, atmosphere and space domains by incorporating classification and attribute codes from standards from those domain.
The most basic representation of anything environmental is its location. The SRM captures and unifies the (geo) spatial models used by SEDRIS. These models include inertial, quasi-inertial, geo-based, as well as non-geo-based purely arbitrary Cartesian systems. And through the coordinate conversion library (a component of the SEDRIS API libraries), the associated SRM software provides a fast, accurate and efficient means to transform coordinates from one frame of reference to another.
The combination of these three core components provides the mechanism for description of environmental data. In a sense, this capability within SEDRIS can be viewed as analogous to a language for describing data about the environment. The SDRM, the EDCS and the SRM enable us to capture and communicate meaning and semantics about environmental data.
The second aspect of SEDRIS builds upon the first, and provides the ability to interchange and share environmental data. We know from practice that it is not enough to be able to clearly represent or describe the data; we must also be able to share such data with others in an efficient manner.
The interchange of data must take into account platform independence, practical efficiency (both in storage and processing) and ease in software development (lowering the barrier to entry). The SEDRIS API and the STF (the SEDRIS format) are designed to achieve these goals. The API and STF, along with the associated tools and utilities, play the primary role in the data interchange, while being semantically coupled to the data representation model. For details on the SEDRIS API and STF, see the SEDRIS website.
These SEDRIS technology components are currently employed in a number of applications dealing with data conversion, data analysis, visualization and a variety of others, and operate on very large data sets used in oceanographic, atmospheric, space and terrain domains. In this regard, SEDRIS does not try to judge, side with, or separate how various domains use environmental data; instead it provides a unifying mechanism for all of them to describe (and subsequently share) such data, without detracting from one or the other.
For additional information on SEDRIS or environmental issues, visit the SEDRIS website.
If you are interested in participating in the ISO SEDRIS standards work, you can contact Jack Cogman, the Convener of WG 8, at firstname.lastname@example.org. For more information about the work of SC 24, visit the committee’s website.
George S. (Steve) Carson is President of GSC Associates of Las Cruces, NM. He specializes in the development of real-time signal and information processing systems and is the Chairman of ISO/IEC JTC 1/SC 24, Computer Graphics and Image Processing.
George S. Carson
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