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Global Map Frequently Asked Questions

These are answers to some of the questions asked about the Global Map program and the data it delivers.

General

Data

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What is Global Map?
Global Map is an international effort by national mapping organizations to produce consistent and accurate mapping data of the world at a resolution of one kilometer (1:1,000,000-scale). There is an International Steering Committee for Global Mapping (ISCGM) that fosters the development of the Global Map. This is done through formal relationships with other international mapping organizations; the preparation of - or revisions to - data specifications; and the development and ratification of best practices for Global Map promotion and delivery. The Global Map Secretariat for the ISCGM is staffed by the Geospatial Information Authority of Japan. The National Atlas of the United States program supplies all American data to the Global Map and represents America on the ISCGM.

Which countries participate?
You will find a list of participating nations online as well as a map of the world showing Global Map progress.

What affiliations does the Global Map have with other international mapping organizations?
Global Map has established formal working relationships with:

  • Global Spatial Data Infrastructure Association (GSDI),
  • Group on Earth Observations (GEO), and
  • One Geology

Where can I learn more about the Global Map?
We offer a Global Map fact sheet in portable document format and you should visit the Global Map Web site for additional information.

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What Global Map data is available from the National Atlas?
Table 1 lists our Global Map vector and raster datasets for the United States. Vector datasets are at a scale of 1:1,000,000. Elevation datasets are at 100-meter resolution.

Layer Feature Name Feature Type
Boundaries Coastline line
Political Boundary area
Political Boundary line
Drainage Aqueduct/Canal/Flume/Penstock line
Inland Water area
Water Course line
Elevation 16-Bit Elevation (in 5 tiles) image
Population Centers Built-up Area point
Transportation Airport point
Ferry Route line
Ferry Port point
Railroad line
Railroad Station point
Road line
Table 1: Currently Available Global Map Datasets of the United States

Some nations also produce the datasets listed in Table 2.

Layer Feature Name Feature Type
Boundaries Political Boundary point
Drainage Miscellaneous (Dam/Weir) point
Miscellaneous(Dam/Weir) line
Miscellaneous (Dam/Weir)
(Dam/Weir/Island/Spring/Water Hole)
point
Population Centers Built-up Area area
Transportation Trails and Track Lines line
Table 2: Additional Global Map Datasets in the Global Map Specifications Version 2.2

The Global Map also includes worldwide datasets of elevation, land cover, and vegetation (percent tree cover) at a resolution of one kilometer. These datasets are tiled in blocks of 30- by 30-degrees and are available only from the Global Map Web site. You may preview land cover and vegetation using Google Earth by downloading tiles in keyhole markup language format.

What's the difference between National Atlas data and Global Map data?
In terms of vector geometry, the lines, points, and areas in these datasets are identical. The difference is in the attributes assigned to these features. The Global Map edition includes just the data fields and attribute values in the Global Map Specifications Version 2.2. National Atlas vector data includes all of the Global Map data fields and attributes plus those in the National Atlas data dictionary.

Global Map elevation datasets are published in a WGS84 geographic projection in Band Interleaved by Line file format. National Atlas elevation data datasets are published in a NAD83 Albers Equal-area projection in GeoTIFF file format.

When should I use Global Map data instead of National Atlas data?
Use our Global Map data when you need consistent small-scale data for the United States and at least one of the other North American countries. Global Map data for Canada and Mexico is available. User registration is required.

Since we only map the United States, download Global Map data for any other nations of interest to you.

Do I download Global Map data from nationalatlas.gov or from the Global Map Web site?
You may download Global Map data for the United States from nationalatlas.gov.

Go to the Global Map Web site to download data for other countries. User registration is required on that site.

Do I have to download Global Map data of the United States or can I connect to it through a mapping service?
Our plans to create Web Map Services and Web Feature Services this year were scrapped when the decision was made to end the National Atlas program. Services for Global Map data should become available from nationalmap.gov in 2015.

Is Global Map data documented?
Yes, Global Map data is documented to the ISO 19115 standard. In the United States, we also offer documentation for our Global Map data that complies with the Content Standard for Digital Geospatial Metadata.

Is the Global Map data specification published online?
Yes. It is available in PDF. You will also find documentation online for each of our Global Map datasets.

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