Introduction |
"Metadata"
is information about data or other information.
"Formal Metadata" is metadata that follows an
FGDC
approved standard
that provides a common set of
terminology, definitions, and information about values to be provided.
Formal metadata are formally-structured documentation of digital data products.
They describe the "who, what, where, when, why, and how" of every aspect of the data.
Formal metadata:
help organize and maintain an organization's internal investment in data,
provide information to data catalogs and clearinghouses (e.g.,
USGS GD or
National), and
provide information to aid data transfers.
Metadata should be recorded during data acquisition, processing, and analysis -- when the information needed for metadata is known, not after the fact, when important information may be lost or forgotten.
Other
metadata information also occurs in the
CMG InfoBank for:
navigation,
gravity,
magnetics,
bathymetry,
seismic,
cameras,
crew,
geodetic postioning,
lines,
metering,
ports,
samples, and
stations.
Why is Metadata important? (from MMI)
Q & A about Metadata (from MMI)
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Background |
In April of 1994, President Clinton signed Executive Order 12906 initiating the National Spatial Data Infrastructure (NSDI), a Federal coordination effort to answer the need for quality spatial information.
A key element of NSDI is the development of a
National Geospatial Data Clearinghouse, a source of descriptions (metadata) to geospatial data that are available to the public.
The Clearinghouse is a distributed network of Internet sites providing metadata to users.
To promote consistency in metadata, the
Federal Geographic Data Committee (FGDC),
an interagency council charged with coordinating the Federal implementation of NSDI, has produced the
Content Standards for Digital Geospatial Metadata.
The standard provides standard terms describing 335 elements common to most geospatial data and specifies the relationships among those terms.
Some elements are
manditory, some are
optional, and some are
manditory if applicable.
"Geospatial data" are defined by EO 12906 as "information that identifies the geographic location and characteristics of natural or constructed features and boundaries on the Earth."
EO 12906 specifically requires Federal agencies to consult the Clearinghouse before collecting new geospatial data, as a potential cost-cutting measure.
Executive Order 12906 requires Federal agencies to document all new digital geospatial data products using standardized metadata.
The standard
defines a "data set" as a "collection of related data."
Using a formal standard helps to exploit the power of worldwide web (WWW) search services by allowing more precise queries that result in fewer, but more relevant documents.
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FAQ's |
Frequently Asked Questions (FAQ's) and
more FAQ's
concerning the FGDC's Content Standard for Geospatial Metadata.
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Sections, Elements, and Structure |
Identification Information
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What is the name of the data set?
Who developed the data set?
What geographic area does it cover?
What themes of information does it include?
How current are the data?
Are there restrictions on accessing or using the data?
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Data Quality Information
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How good are the data?
Is information available that allows a user to decide if the data are suitable for his or her purpose?
What is the positional and attribute accuracy?
Are the data complete?
Were the consistency of the data verified?
What data were used to create the data set, and what processes were applied to these sources?
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Spatial Data Organization Information
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What spatial data model was used to encode the spatial data?
How many spatial objects are there?
Are methods other than coordinates, such as street addresses, used to encode locations?
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Spatial Reference Information
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Are coordinate locations encoded using longitude and latitude?
Is a map projection or grid system, such as the State Plane Coordinate System, used?
What horizontal and vertical datums are used?
What parameters should be used to convert the data to another coordinate system?
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Entity and Attribute Information
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What geographic information (roads, houses, elevation, temperature, etc.) is included?
How is this information encoded?
Were does used?
What do the codes mean?
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Distribution Information
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From whom can I obtain the data?
What formats are available?
What media are available?
Are the data available online?
What is the price of the data?
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Metadata Reference Information
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When were the metadata compiled?
By whom?
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Tools |
"xtme" (X Tree Metadata Editor) is a USGS
menu based metadata editor that may be used to create formal metadata by allowing entry of values for metadata elements by direct keyboard entry.
(by Peter Schweitzer)
"cns" (Chew and Spit) is a USGS
formal metadata editor that may be used to create formal metadata and to restructure it into standard format.
(by Peter Schweitzer)
"mp" (Metadata Parser) is a USGS metadata parser
that may be used to verify compliance to the standard and to convert proper metadata to SGML, HTML, text, and NASA's Directory Interchange Format (DIF).
(by Peter Schweitzer)
"makefmeta" (Make Formal Metadata) is a USGS application that utilizes standard CMG InfoBank files and structure to create Activity-specific formal metadata.
(by Clint Steele)
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Submitting metadata |
Metadata transferred to a Clearinghouse node must be encoded in Standard Generalized Markup Language (SGML).
By special arrangement USGS GD metadata may be transferred to the USGS GD Clearinghouse node if it is acceptable to the USGS metadata parser "mp".
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Retrieving metadata |
Metadata are retrieved from a Clearinghouse node (e.g.,
USGS GD or
National) using a web browser or other HTTP agent.
Activity specific metadata are also accessible through the
CMG InfoBank.
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"How often misused words generate misleading thoughts." --
Herbert Spencer
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