Global Land Survey Digital Elevation Model (GLSDEM)
Entry ID: GLCF_glsdem

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Summary
Abstract: The Global Land Survey Digital Elevation Model (GLSDEM) is a spatial data collection crucial to new global imagery products from NASA and the USGS. In the late 1990s, the U.S. Congress set aside funding to stimulate the use of remotely sensed imagery and products through the Science Data Purchase (SDP) program. One of the SDP collections is GeoCover - a coordinated dataset of orthorectified Landsat imagery available in three epochs. The GeoCover collection was orthorectified using classified control points and the GTOPO30 global elevation model. Since it first became available, the GeoCover collection was and still is a big success, encouraging use of remotely sensed imagery for Earth science research around the world, and bridging the use of imagery into myriad other uses. The geodetic accuracy of the input elevation model, however, was less than ideal so that some GeoCover scenes suffered from poor geo-registration.

With the advent of higher precision DEMs for the entire planet, the Landsat images used to make the GeoCover collection were reprocessed for higher geo-locational quality into the Global Land Survey (GLS) collection. The GLS collection contains the same three epochs as in GeoCover - 2000, 1990, 1975 - plus a fourth epoch focused on 2005. The GLS2005 collection includes imagery from the TM, ETM+ and ALI sensors. The GLS collection was made possible by the development of more accurate elevation models with global or regional coverage, including the National Elevation Dataset (NED) of the USA, the Canadian Digital Elevation Dataset (CDED) of Canada and the Shuttle Radar Topography Mission (SRTM) covering most of the globe. In order to orthorectify the GLS scenes, the elevation data was coordinated into the GLSDEM product. The GLSDEM product is of 3 arc second (90m) resolution and in Geographic coordinates with a WGS-84 datum. GLCF produces GLSDEM files in WRS-2 tiles in the GeoTIFF format, UTM projection and horizontal WGS 84 datum of the corresponding GLS datasets. For each path/row, the original USGS Degree tiles are mosaicked and subset with a 9km buffer to reproduce the GLSDEMs into the Landsat WRS-2 tiling system. The GLSDEM degree tiles may be obtained from EROS Data Center, USGS or the GLCF. The WRS-2 edition of the GLSDEMs is available only through the GLCF.

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Description: Global Land Survey Digital Elevation Model (GLSDEM)


Geographic Coverage
 N: 90.0 S: -90.0  E: 180.0  W: -180.0

Data Set Citation
Dataset Originator/Creator: USGS
Dataset Title: Global Land Survey Digital Elevation Model (GLSDEM)
Dataset Release Place: College Park, Maryland
Dataset Publisher: Global Land Cover Facility, University of Maryland
Online Resource: http://glcf.umd.edu/data/glsdem/


Location Keywords
GEOGRAPHIC REGION > GLOBAL


Data Resolution
Latitude Resolution: 90 m
Longitude Resolution: 90 m


Science Keywords
LAND SURFACE >TOPOGRAPHY >LANDFORMS    [Definition]
LAND SURFACE >TOPOGRAPHY >TERRAIN ELEVATION    [Definition]


ISO Topic Category
ELEVATION


Platform
DEM >Digital Elevation Model    [Information]
LANDSAT-7    [Information]


Instrument
ALI >Advanced Land Imager    [Information]
ETM+ >Enhanced Thematic Mapper Plus    [Information]
TM >Thematic Mapper    [Information]


Project
ESIP >Earth Science Information Partners Program    [Information]
REASON >Research, Education, and Applications Solution Network    [Information]


Use Constraints
Use is free to all; effectively held by USGS & NASA. The ultimate copyright and ownership of the product, however, is held by the citizens of the United States of America, the Republic of Germany, and the Dominion of Canada.

As a courtesy, please credit the Global Land Cover Facility (GLCF) as the source for this data set in some manner. Our suggestion: Source for this data set was the Global Land Cover Facility, www.landcover.org.


Keywords
Digital Elevation Model
Land Cover
Model


Data Set Progress
COMPLETE


Originating Center
USGS


Data Center
Global Land Cover Facility, University of Maryland    [Information]
Data Center URL: http://glcf.umd.edu/

Data Center Personnel
Name: GLOBAL LAND COVER FACILITY
Email: glcf at umd.edu
Contact Address:
Global Land Cover Facility
3166 A.V. Williams Bldg
University of Maryland
City: College Park
Province or State: MD
Postal Code: 20742
Country: USA



Distribution
Distribution_Media: Online FTP
Fees: No fees


Personnel
GLOBAL LAND COVER FACILITY
Role: TECHNICAL CONTACT
Email: glcf at umd.edu
Contact Address:
Global Land Cover Facility
3166 A.V. Williams Bldg
University of Maryland
City: College Park
Province or State: MD
Postal Code: 20742
Country: USA


TYLER B. STEVENS
Role: DIF AUTHOR
Phone: (301) 614-6898
Fax: 301-614-5268
Email: Tyler.B.Stevens at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA



Creation and Review Dates
DIF Creation Date: 2011-02-03
Last DIF Revision Date: 2014-09-15

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