The Value of Metadata

Two very similar paintings of circus performers by Picasso from 1904 are put on the auction block; one brings tens of millions of dollars, the other hundreds of thousands. What is the difference? In one case, the ownership of the painting can be traced through sales slips and auction house records back to the estate of Picasso's dealer. The other painting appeared suddenly on the art market. They both appear to be original Picasso's but one lacks documentation. How can one be sure the undocumented painting is authentic?

Just as a work of art can change hands many times, so can geospatial data. Once created, data can travel almost instantaneously through a network and be used for any number of different kinds of spatial analysis. Once transformed, these data can then be retransmitted to other users. Change is the essence of geospatial data in a networked environment. The word metadata shares the same Greek root as the word metamorphosis. Meta means change and metadata, or "data about data" describe the origins of and track the changes to geospatial data.

Metadata can help the city planner, the graduate student in geography, or the forest manager find and use geospatial data, but they also benefit the primary creator of the data by maintaining the value of the data and assuring their continued use over a span of years.

What are Metadata?

The concept of metadata is familiar to most people who deal with spatial issues. A map legend is pure metadata. The legend contains information about the publisher of the map, the publication date, the type of map, a description of the map, spatial references, the map's scale and its accuracy, among many other things. Metadata are simply that type of descriptive information applied to a digital geospatial file. They're a common set of terms and definitions to use when documenting geospatial data. Most digital geospatial files now have some associated metadata.

Why bother with Metadata?

Metadata helps people who use geospatial data find the data they need and determine how best to use it. Metadata benefit the data -producing organization as well. As personnel change in an organization, institutional knowledge leaves the organization. Undocumented data can lose their value. Subsequent workers may have little understanding of the contents and uses for a digital data base and may find they can't trust results generated from these data. Also, lack of knowledge about other organizations' data can lead to duplication of effort. It may seem burdensom to add the cost of generating metadata to the cost of data collection, but in the long run metadata is worth it.

Why use a standard?

When producing a map, the cartographer must organize all the descriptive information that goes into the map legend in a particular format. Titles are put in a specific place, tic marks are made a certain way, meters may be used instead of feet, and so forth. A metadata standard is simply a common set of terms and definitions that describe geospatial data.

What standard should be used?

The Federal Geographic Data Committee (FGDC) originally adopted a content standard for metadata in 1994, revised in 1998. According to Executive Order 12096 signed by President Clinton on April 11, 1994, all Federal agencies are ordered to use this standard to document geospatial data created as of January, 1995. This standard provides a consistent approach and format for the description of data characteristics. The standard was developed over a two-year period, with extensive review by professionals at all levels of government. The standard provides a way for data users to know:

These standards have been implemented beyond the federal level with State and local governments adopting the metadata standard as well. The FGDC is tasked by Executive Order 12906 to develop procedures and assist in the implementation of a distributed discovery mechanism, clearinghouses, for digital geospatial data. Using the data elements defined in the standard, governmental, non-profit, and commercial participants worldwide can make their collections of spatial information searchable and accessible on the Internet using free reference implementation software developed by the FGDC. State, regional, local, and other data producers have established clearinghouses to provide public access to their geospatial data.

How can Metadata be produced?

The information needed to create metadata is often readily available when the data are collected. A small amount of time invested at the beginning of a project may save money in the future. Data producers and users cannot afford to be without documented data. The initial expense of documenting data clearly outweighs the potential costs of duplicated or redundant data generation.

Metadata creation applications are available integrated into GIS applications, as well as stand-alone and Internet applications. Most create fully FGDC compliant metadata and some offer the ability to extend the FGDC standard with FGDC Profiles or Extensions, and implementations of the ISO 19115 Metadata Standard. Data managers may provide these metadata to NSDI clearinghouses to allow easier access to their data and thereby broaden their cooperator and consumer base.

Why use metadata?

In 1969, humans landed on the Moon. Data from that era are still being used today, and it is reasonable to assume that today's geospatial data could still be used in the year 2020 and beyond to study climate change, ecosystems, and other natural processes. Implementing metadata standards increase the value of such data by facilitating data sharing through time and space.

The value of Picasso's painting does not solely depend on Picasso signing the work; a signature can be easily forged. Information about the painting, where it came from and where it had been, increased its value. So when a manager launches a new project, investing a small amount of time and resources at the beginning can pay dividends in the future.

For more information

If you would like to explore available training or seek information about the FGDC Metadata Standard or the National Geospatial Data Clearinghouse contact:

fgdc@fgdc.gov