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 which of the summits of Mt.
Everest
or Chimborazo
is 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
survey, 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.
Global 1-kilometer map
This map is derived from
GTOPO30 data that
describes the elevation of Earth's terrain at intervals of 30
arcseconds (approximately 1 km). It uses color and shading instead
of contour lines to indicate elevation.
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| Each tile is available at a resolution of 1800 ×
1800 pixels (approximate file size 1 MB, 60 pixels = 1 degree, 1
pixel = 1 minute) |
See also
External links