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New System for Spatial

The Washington State Department of Transportation takes a GIS standard for a test drive.

Spatial metadata are basically computerized card catalogs on geospatial data. Without them, prospective users would have difficulty judging the availability, reliability and appropriateness of the original spatial data for their particular purpose. If there is an accepted standard of metadata documentation, as there is for library card catalogs, then a relational database-management system can be designed around that standard, allowing users to index, store and access metadata files via intranet or the Internet.

Until the 1990s, no widely accepted standards for geospatial metadata existed; public and private organizations simply devised their own methods of documentation. Among government agencies, where sharing data is more prevalent than in the private sector, this often led to redundancies and inefficient use of data resources. In 1994, a standard for documenting spatial metadata emerged, when the Federal Geographic Data Committee (FGDC) approved the Content Standard for Digital Geospatial Metadata.

The FGDC standard was developed as part of the National Spatial Data Infrastructure, a nationwide collection of clearing-houses and nodes, mandated by executive order to promote the sharing of geospatial data. The FGDC standard has since been adopted by many public and private organizations.

Assembling the GIS Puzzle

The Washington State Department of Transportation (WSDOT) was one of the first agencies to adopt the FGDC standard. According to GIS Data Administrator Gordon Kennedy, the agency faced the task of documenting geospatial data in multiple formats created by six regional offices over 15 years.

"We had all these digitized files," Kennedy said, "but the question was, how reliable is the data. To know what we were dealing with when we exchanged files among regional offices and other departments, we had to document our map data very methodically and build a central metadata repository that could be queried by anyone within the DOT. To accomplish that, we needed a database-management system designed around the FGDC metadata standard."

In addition to maintaining 7,000 state highway miles through five mountain passes, WSDOT operates the largest ferry system in North America, carrying 14 million passengers and 10 million vehicles annually throughout Puget Sound and the San Juan Islands. It also funds intermodal programs, including trains and buses. Given the potential volume and variety of geospatial data relating to these systems, a database-management system designed around the FGDC standard had to be capable of importing metadata in multiple formats manually or through bulk loading.

SMMS Version 1.01

After evaluating several products, WSDOT began testing Spatial Metadata Management System (SMMS) Version 1.01, developed by Michael Brackett and Enabling Technology Inc. of Richland, Wash. The decision to test the product was based on several factors; the firm provides systematic support that includes online software assistance, upgrades and regular releases. Also, SMMS allows data sets to be manually or bulk loaded. Standard format reports of metadata are stored in structured ASCII, enabling users to easily access, browse, update, share and publish data from any platform, via intranet or the Internet. The system does not dictate the fields to be answered or the sequence of responding; data completeness is left to the user.

Version 1.01, which WSDOT is currently using, is a Windows-based system built on a Microsoft Access 97 relational database. This is a single-user setup, not a network application; three people in different offices each have a copy, but only one person can use it at a time.

The FGDC standard defines seven major categories of metadata: identification, data quality, organization, spatial-data reference, attributes and entities, distribution and metadata reference. Within each of these are subcategories and layers of increasingly complex detail. In SMMS, these entities are accessed through a series of screens, pull-down menus, tabs and subtabs. Major categories have buttons along the bottom of the screen, allowing users to move quickly between them. Directions and keywords for data entry are accessed by clicking on the different fields. Both user definitions and FGDC definitions are built in. There are approximately 300 fields in the FGDC standard.

Kennedy pointed out that not every data set requires the same amount of time or level of detail to establish satisfactory identification.

"We are not trying to fill in every mandatory field the federal standard calls for," he said. "Answering just the essential fields may be sufficient, and that takes a few minutes. Responding to all the mandatory fields in the federal standard takes 15 to 30 minutes of data entry, but the person would have to have all the facts at hand before starting. That might require some research."

New Releases

WSDOT is now testing SMMS Version 2.0, a relational database-management system built on a Microsoft Structured Query Language (SQL) server. The SQL runs on Windows 95/NT, OS/2, NetWare, Unix, and VAT servers. It is a true network application capable of accommodating concurrent users. In addition to its capabilities for storing and accessing metadata across an intranet or the Internet, 2.0 will accept ASCII text files of metadata in FGDC format, regardless of the client's choice of metadata data-management systems. For WSDOT, this means increased facility in handling the volume and diversity of metadata expected from six regional offices, 39 counties and 275 cities.

"If they follow the FGDC standard," Kennedy said, "we will be more than halfway home in terms of being able to import their metadata into SMMS 2.0." He added that the switch to version 2.0 will just be a matter of porting the tables from the access database to the SQL server database. Since Micro-soft is the vendor for both servers, WSDOT is not anticipating difficulties in transferring data.

Weakness Corrected

The weakness of SMMS 1.01 and 2.0 is that neither provides a direct link between metadata and the actual data; the two are separate files. Without a hot link between them, changes in the actual data can not be directly transmitted to the related metadata in the repository. According to Eric Meyer, Enabling Technology's marketing development manager, that capability will be in SMMS 3.0, slated to be released early next year.

"A direct GIS data browser, based on ESRI's MapObjects Technology, is embedded in the product," he said. "It will allow users to pull up maps, browse, identify, pan and zoom in on spatial data from within SMMS and update related metadata with the touch of a button."

Model for Metadata Management

The model being proposed for WSDOT is the data steward, an office or person with certain responsibilities, including metadata documentation, for all DOT data. The data administrator then acts as a clearing-house for data publishing.

"If the Environmental Affairs Office wants to publish a wetlands layer and make it available to users throughout the state, they send the data here first," Kennedy explained. "If the metadata are complete and in proper format, and this is a data layer of enterprise-wide interest, then it is accepted, published and replicated for regional offices' use. This approach gives us some control over the standards; data do not go out without proper documentation."

Establishing a Repository

WSDOT's immediate objective is to build a database for metadata storage. The agency will then generate a report from that database in the form of a structured ASCII text file that can be imported and indexed by the University of Washington Map Library. The library is now a global clearing-house for geospatial metadata and is part of the National Spatial Data Infrastructure. In the clearing-house, the metadata will be accessible to anyone via the Internet.

Kennedy said the department is still working with SMMS Version 1.01. "Our only investment has been for the three seats, to learn about the product and see if it is suitable for our purposes," he said. "I think it will be. But for WSDOT, it needs to be a SQL server product, a database that can function effectively on an intranet or the Internet. Version 2.0 is expected to have these capabilities. When SMMS gets to this level, the technical review people will take it seriously and say, 'Let's elevate this to be a sanctioned product at WSDOT.'"

Bill McGarigle is a writer specializing in communications and information technology. He is based in Santa Cruz, Calif.

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