elevation

[el-uh-vey-shuhn]

elevation, vertical distance from a datum plane, usually mean sea level to a point above the earth. Often used synonymously with altitude, elevation is the height on the earth's surface and altitude, the height in space above the surface. The elevation of a feature is calculated through such surveying techniques as trigonometric triangulation and aerial photogrammetry. Elevation is represented by using contours of equal elevation lines, three-dimensional computer graphics representation, or molded three-dimensional plastic models.

The Columbia Electronic Encyclopedia Copyright © 2004.
Licensed from Columbia University Press

Elevation

The elevation of a geographic location is its height above a fixed reference point, often the mean sea level. Elevation, or geometric height, is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit.

Less commonly, elevation is measured using the center of the Earth as the reference point. Due to equatorial bulge, there is debate whether the summits of Mt. Everest or Chimborazo are at the higher elevation, as the Chimborazo summit is further from the Earth's center while the Mt. Everest summit is higher above mean sea level.

Maps and GIS

A topographical map is the main type of map used to depict elevation, often through use of 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 in GIS.

To determine elevation of a place, it must be surveyed, in reference to a ground control point.

Topography

The elevation of a mountain usually refers to its summit. The elevation of a hill also refers to the summit. A valley's elevation is usually taken from the lowest point but is often taken all over the valley.