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A digital elevation model (DEM) or digital surface model (DSM) is a 3D computer graphics representation of elevation data to represent terrain or overlaying objects, commonly of a planet, moon, or asteroid. A "global DEM" refers to a discrete global grid.
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.
Heightmaps are an ideal way to store digital terrain elevations; compared to a regular polygonal mesh, they require substantially less memory for a given level of detail. Most modern 3D computer modelling programs are capable of using data from heightmaps in the form of bump , normal , or displacement maps to quickly and precisely create ...
A topographical map is the main type of map used to depict elevation, often through contour lines. In a Geographic Information System (GIS), digital elevation models (DEM) are commonly used to represent the surface (topography) of a place, through a raster (grid) dataset of elevations. Digital terrain models are another way to represent terrain ...
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 ...
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]
Section of topographical map of Nablus area with contour lines at 100-meter intervals. Heights are colour-coded. Heights are colour-coded. In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting ...
Level 1 7.5-minute 30-minute Created by autocorrelation or manual profiling from aerial photographs May be derived from a wide variety of sources using any of a number of USGS approved techniques and instrumentation Level 2 All series Created from digital line graph (DLG) contours or equivalent, from any USGS map series up to 1:100000 scale