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National Geophysical Data Center: All free data from the NGSC. Includes elevation models, land cover, seismology, etc. The Geospatial Platform: Search for and download a wide variety of datasets from this portal developed by the member agencies of the Federal Geographic Data Committee through collaboration with partners and stakeholders.
The data is free to download non-commercially and through the developer's website at a cost commercially. An alternative free global DEM is called GTOPO30 (30 arcsecond resolution , c. 1 km along the equator) is available, but its quality is variable and in some areas it is very poor.
GTOPO30 is a digital elevation model for the world, developed by United States Geological Survey (USGS). It has a 30-arc second resolution (approximately 1 km), [1] and is split into 33 tiles stored in the USGS DEM file format.
EPSG Geodetic Parameter Dataset (also EPSG registry) is a public registry of geodetic datums, spatial reference systems, Earth ellipsoids, coordinate transformations and related units of measurement, originated by a member of the European Petroleum Survey Group (EPSG) in 1985.
On 29 June 2009, the Global Digital Elevation Model (GDEM) was released to the public. [8] [9] A joint operation between NASA and Japan's Ministry of Economy, Trade and Industry (METI), the Global Digital Elevation Model is the most complete mapping of the earth ever made, covering 99% of its surface. [10]
A global relief model, sometimes also denoted as global topography model or composite model, combines digital elevation model (DEM) data over land with digital bathymetry model (DBM) data over water-covered areas (oceans, lakes) to describe Earth's relief. A relief model thus shows how Earth's surface would look like in the absence of water or ...
DTED (or Digital Terrain Elevation Data) is a standard of digital datasets which consists of a matrix of terrain elevation values, i.e., a Digital Elevation Model.This standard was originally developed in the 1970s to support aircraft radar simulation and prediction.
Groups of scientists have worked on algorithms to fill the voids of the original SRTM (v2.1) data. Three datasets offer global coverage void-filled SRTM data at full (3-arcsecond) resolution: The CGIAR-CSI version 4 provides the best global coverage using interpolation. [12]