Search results
Results from the WOW.Com Content Network
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.
The DTED format for level 0, 1 and 2 is described in U.S. Military Specification Digital Terrain Elevation Data (DTED) MIL-PRF-89020B, and amongst other parameters describes the resolution for each level: Level 0 has a post spacing of approximately 900 meters. Level 1 has a post spacing of approximately 90 meters.
The National Elevation Dataset (NED) consists of high precision topography or ground surface elevation data (digital elevation model) for the United States. It was maintained by the USGS and all the data is in the public domain. Since the 3D Elevation Program came online, the NED was subsumed [1] into The National Map as one of its layers of ...
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
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 ...
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 ...
Height fields (also known as "2 1/2 dimensional surfaces") model three-dimensional phenomena by a single functional surface, in which elevation is a function of two-dimensional location, allowing it to be represented using field techniques such as isolated points, contour lines, raster (the digital elevation model), and triangulated irregular ...
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 ...