Appendix D: Related Technical Information and Programs
MetadataContent Standards for Digital Geospatial Metadata. June 8, 1994, Federal Geographic Data Committee, Washington, DC.
Metadata are data about the content, quality,
condition, and other characteristics
of data. Metadata are required for geospatial data
contributed to the framework
and referenced through the clearinghouse. The
metadata standard provides a common set of
terminology and definitions for concepts and
components related to those metadata.
Cadastral Data Content Standard for the National Spatial Data Infrastructure. 1996, Cadastral Subcommittee, Federal Geographic Data Committee, Washington, DC.
The cadastral data standard provides common definitions for cadastral information found in public records, which facilitate the effective use, understanding, and automation of land records. The standard also provides guidance and direction for land records and land surveying professionals on standardized attribute values and definitions, which will improve land records creation, management, and use.
Use of the standard should standardize attribute
values, which will enhance data sharing. It also
resolves discrepancies related to the use of
homonyms and synonyms in federal land record
systems, which minimizes duplication among those
systems. The cadastral standard will mesh with the
data model for the cadastral data theme of the
framework. While the model is being developed, the
cadastral standard can serve as a guide for
developing and sharing cadastral data.
Spatial Data Exchange
Spatial Data Transfer Standard. June 10, 1994, Federal Information Processing Standards Publication. FIPSPUB 173-1, U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technology, U.S. Government Printing Office, Washington, DC.
The SDTS is a mechanism for transferring spatial data between dissimilar computer systems. The SDTS specifies exchange constructs, addressing formats, structure, and content for spatially referenced vector and raster data. The components of the SDTS are a conceptual model, specifications for a quality report, transfer module specifications, data dictionary specifications, and definitions of spatial features and attributes. The SDTS may be useful for data exchange among systems that have not conformed to framework standards or have not formed their own community standards.
National Spatial Reference System
Coordinates should be expressed in latitude and longitude. All the framework data will then be in the same coordinate system and applicable in all areas of the country.
The North American Datum of 1983 (NAD 83) should be used for horizontal data. The North American Vertical Datum of 1988 (NAVD 88) should be used for vertical data. The use of these datums establishes a common reference for all horizontal and vertical data in the framework. These datums provide the necessary linkages for GPS data and are supported by the GPS continuously operating reference stations. The Federal Geodetic Control Subcommittee of the FGDC has affirmed the NAD 83 and NAVD 88 for official use for civilian surveying and mapping activities.
National Geospatial Data Clearinghouse
The National Geospatial Data Clearinghouse is a distributed, electronically connected network of geospatial data producers, managers, and users. It is a referral service for determining who has what data. It provides access to data through (in descending order of preference) an on-line link, an order form, or contact information for the organization that distributes the data. It is not a central repository where data sets are stored. The clearinghouse provides a means to locate and access framework data (either through direct file transfer or through an ordering capability) and is based on the Z39.50 protocol for search for the Internet. The FGDC metadata standard provides the basis for the searchable data elements. The metadata may reside in flat files or database management systems at the host server, as long as access through a Z39.50 search capability is provided.
National Digital Orthophoto Program
The goal of the National Digital Orthophoto Program (NDOP) is to produce digital orthophoto quadrangle (DOQ) coverage of the conterminous United States by 2002 though cooperative funding agreements with federal, state, and local agencies. Production began in 1993. Plans are to update the DOQs on a 10-year cycle for most areas and a 5-year cycle in areas where land use change is more rapid. NDOP will attempt to accommodate regional, state, and local update schedules. The production strategy is to accomplish the majority of the work by contracting with the private sector.