Theelevation of ageographiclocation is itsheight above or below a fixed reference point, most commonly a referencegeoid, amathematical model of theEarth'ssea level as anequipotentialgravitationalsurface (seeGeodetic datum § Vertical datum).The termelevation is mainly used when referring to points on the Earth's surface, whilealtitude orgeopotential height is used for points above the surface, such as an aircraft in flight or aspacecraft in orbit, anddepth is used for points below the surface.
Elevation is not to be confused with the distance from the center of the Earth. Due to theequatorial bulge, the summits ofMount Everest andChimborazo have, respectively, the largest elevation and the largestgeocentric distance.
In aviation, the termelevation oraerodrome elevation is defined by theICAO as the highest point of the landing area. It is often measured in feet and can be found in approach charts of the aerodrome. It is not to be confused with terms such as thealtitude or height.[1]
GIS orgeographic information system is a computer system that allows for visualizing, manipulating, capturing, and storage of data with associated attributes. GIS offers better understanding of patterns and relationships of the landscape at different scales. Tools inside the GIS allow for manipulation of data for spatial analysis or cartography.
Atopographical map is the main type ofmap used to depict elevation, often throughcontour lines.In aGeographic Information System (GIS),digital elevation models (DEM) are commonly used to represent the surface (topography) of a place, through araster (grid) dataset of elevations.Digital terrain models are another way to represent terrain in GIS.
USGS (United States Geologic Survey) is developing a 3D Elevation Program (3DEP) to keep up with growing needs for high quality topographic data. 3DEP is a collection of enhanced elevation data in the form of high quality LiDAR data over the conterminous United States, Hawaii, and the U.S. territories. There are three bare earth DEM layers in 3DEP which are nationally seamless at the resolution of 1/3, 1, and 2 arcseconds.[2]
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