Global Land One-kilometer Base Elevation (GLOBE)
Digital Elevation Data CD-ROM: Version 1.0
The NOAA National Geophysical Data Center (NGDC) is pleased to announce the first full release of the Global Land One-kilometer Base Elevation (GLOBE) digital elevation data set. GLOBE is an international effort to create a global digital elevation model (DEM) on a nominal 1-kilometer grid. GLOBE is an activity of the Committee on Earth Observation Satellites (CEOS), and is part of Focus I of the International Geosphere-Biosphere Programme's Data and Information System (IGBP-DIS).
A Variety of Sources
Data came from 11 sources, via 18 combinations of source/lineage processing. Scientists compiled DEMs available at griddings of 1-km or smaller, adding or making the best available grids for other areas to complete global coverage of land areas. Organizations in all settled continents contributed in some way to source data or post-source processing and quality control that ultimately found their way into GLOBE.
Source data include satellite imagery, aerial photography, satellite altimetry, cadastral survey data, and hardcopy topographic maps converted to digital format. The source data were converted to 16-bit binary raster grids by a variety of techniques, including stereoprofiling, image pattern recognition, contour-to-grid and point-to-grid surface generation.
Selection of GLOBE Data
Many areas had more than one candidate data set. Candidates were compared for final selection and mosaicked into the full global DEM. Guidance was provided by periodic meetings of the CEOS GLOBE Task Team, and by interaction with IGBP-DIS. The final GLOBE data set and documentation received peer review on four continents.
The GLOBE project includes two versions of GLOBE: (1) a completely unrestricted version with full global coverage, which has no copyright or security restrictions on its distribution, and (2) a version that honors copyright, where the higher quality of the copyright data merited such inclusion, and where distribution of such data was licensed to NGDC on behalf of the GLOBE Task Team.
Currently, dual versions of GLOBE coverage exists for Australia, courtesy of the Australian Surveying and Land Information Group (AUSLIG). AUSLIG allowed NGDC to make a 30-arc-second grid from copyright AUSLIG source data; these data are currently available on the GLOBE CD-ROMs only.
Version 1.0 Differs from Prototypes
GLOBE Version 1.0 differs from two prototype CD collections (Versions 0.1 and 0.5, distributed in 1995 and 1997). Unlike Versions 0.1 and 0.5, GLOBE Version 1.0 is a full global compilation covering all land areas. It is the first global elevation data set with such extensive input, documentation, and peer review.
Some users who want the multiple representations (computed cell maximum, minimum, mean, and discrete sample value) available on GLOBE Prototype Version 0.5 may wish to acquire that data set from NGDC. Contact NGDC for more information.
Availability of GLOBE Data
On the Web. GLOBE data, documentation, and visualizations are available at no charge at http://www.ngdc.noaa.gov/mgg/topo/globe.html. This site may appeal to those with fast Internet access, but will not have the copyright data for Australia, at least initially.
On CD-ROM. The CD-ROM collection (four CDs) is available from NOAA/NNDC/National Geophysical Data Center. The 138 page documentaion manual originally distributed with the cds is out of print. The manual is included on the cds as a printable .pdf file (Adobe Acrobat, which has free reader downloadable from http://www.adobe.com) The documentation is also availabe on the GLOBE website. The CD version may be preferred by those desiring to have the data set "in hand." It also contains the best available data for Australia, at 30". For more information, please write or call us, and for discounted pricing use the online store (see "On CD-ROM" link).