Global Land Survey Digital Elevation Model (GLSDEM)

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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.

Citation Format: Author (Publication Date), Collection Name, Image Name, Processing Level, Publisher, Publisher Location, Product Coverage Date.

Citation Parameters Example:

• Author: USGS
• Publication Date: "2008"
• Collection Name: Global Land Survey Digital Elevation Model (GLSDEM)
• Image Name: GLSDEM tile for the corresponding Landsat WRS-2 path row
• Publisher: Global Land Cover Facility, University of Maryland
• Publisher Location: College Park, Maryland

Full Example Citation: USGS (2008), GLSDEM, 90m scene GLSDEM_p123r024_utmz13, Global Land Cover Facility, University of Maryland, College Park, Maryland.

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.

Source for this data set is the Global Land Cover Facility, www.landcover.org.