Descrizione

The Global GIS Database was derived from National Imagery and Mapping
Agency’s (NIMA) Vector Map Level 0 (VMAP0) database (Digital Chart of the World,
3d ed.). The following is quoted directly from USGS’s Global GIS Database
website (and published CD-ROMs):
“The Vector Map (VMap) Level 0 database represents the third edition of
the Digital Chart of the World. VMap Level 0 is a comprehensive 1:1,000,000
scale vector basemap of the world. It consists of cartographic, attribute, and
textual data … . The primary source for the database is the National Imagery
and Mapping Agency’s (NIMA) Operational Navigation Chart (ONC) series. This is
the largest scale unclassified map series in existence that provides consistent,
continuous global coverage of essential basemap features.”
The Operational Navigation Chart (ONC) series was assembled at a scale of
1:1,000,000 from medium- and low-altitude aerial photographs, and the themes
were digitized from the photographs. Additional sources enhanced the accuracy
of the dataset.

Supplemental Information:
The Global GIS Database world airport dataset contained data on 7016
airports in the Circum-Pacific region. The ACI data, which were attached to the
Global GIS Database dataset by International Air Transport Association (IATA)
codes, provided additional data on passenger and cargo load for 670 of the 7016
airports.
Although the “Global GIS Database: Digital Atlas of the Earth” DVD-ROM
publication (DDS-62-H) is at present [Summer 2002] still “in press,” the USGS
has published CD-ROMs in the “Global GIS Database” series for three areas in the
Circum-Pacific region (all are available from U.S. Geological Survey; see below
for address): DDS-62-A, Digital Atlas of Central and South America (Hearn and
others, 2000); DDS-62-C, Digital Atlas of South Asia (Hearn and others, 2001);
and DDS-62-D, Digital Atlas of South Pacific (Hearn and others, 2001).

Thomas J. Casadevall, Theodore B. Thompson and Tom Fox