Elevation

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The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vertical datum). The term elevation 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, and depth is used for points below the surface.

Contents

Elevation is not to be confused with the distance from the center of the Earth. Due to the equatorial bulge, the summits of Mount Everest and Chimborazo have, respectively, the largest elevation and the largest geocentric distance.

Sign at 8,000 feet (2,438 m) in the San Bernardino Mountains of southern California (2009) SanBernardinoMountains8000feetsign.JPG
Sign at 8,000 feet (2,438 m) in the San Bernardino Mountains of southern California (2009)
Vertical distance comparison Vertical distances.svg
Vertical distance comparison
Elevation histogram of the Earth's surface, of which approximately 71% is covered with water Earth elevation histogram 2.svg
Elevation histogram of the Earth's surface, of which approximately 71% is covered with water

Maps and GIS

Part of a topographic map of Haleakala (Hawaii), showing elevation. Topomapcropped.jpg
Part of a topographic map of Haleakala (Hawaii), showing elevation.
Landsat Image over SRTM Elevation by NASA, showing the Cape Peninsula and Cape of Good Hope, South Africa in the foreground. Satellite image of Cape peninsula.jpg
Landsat Image over SRTM Elevation by NASA, showing the Cape Peninsula and Cape of Good Hope, South Africa in the foreground.

GIS or geographic 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.

Heightmap of Earth's surface (including water and ice) in equirectangular projection, normalized as 8-bit grayscale, where lighter values indicate higher elevation. Srtm ramp2.world.21600x10800.jpg
Heightmap of Earth's surface (including water and ice) in equirectangular projection, normalized as 8-bit grayscale, where lighter values indicate higher elevation.

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.

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. [1]

Global 1-kilometre 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 hypsometric tints instead of contour lines to indicate elevation.

Topographic30deg N60W150.png Topographic30deg N60W120.png Topographic30deg N60W90.png Topographic30deg N60W60.png Topographic30deg N60W30.png Topographic30deg N60W0.png Topographic30deg N60E0.png Topographic30deg N60E30.png Topographic30deg N60E60.png Topographic30deg N60E90.png Topographic30deg N60E120.png Topographic30deg N60E150.png
Topographic30deg N30W150.png Topographic30deg N30W120.png Topographic30deg N30W90.png Topographic30deg N30W60.png Topographic30deg N30W30.png Topographic30deg N30W0.png Topographic30deg N30E0.png Topographic30deg N30E30.png Topographic30deg N30E60.png Topographic30deg N30E90.png Topographic30deg N30E120.png Topographic30deg N30E150.png
Topographic30deg N0W150.png Topographic30deg N0W120.png Topographic30deg N0W90.png Topographic30deg N0W60.png Topographic30deg N0W30.png Topographic30deg N0W0.png Topographic30deg N0E0.png Topographic30deg N0E30.png Topographic30deg N0E60.png Topographic30deg N0E90.png Topographic30deg N0E120.png Topographic30deg N0E150.png
Topographic30deg S0W150.png Topographic30deg S0W120.png Topographic30deg S0W90.png Topographic30deg S0W60.png Topographic30deg S0W30.png Topographic30deg S0W0.png Topographic30deg S0E0.png Topographic30deg S0E30.png Topographic30deg S0E60.png Topographic30deg S0E90.png Topographic30deg S0E120.png Topographic30deg S0E150.png
Topographic30deg S30W150.png Topographic30deg S30W120.png Topographic30deg S30W90.png Topographic30deg S30W60.png Topographic30deg S30W30.png Topographic30deg S30W0.png Topographic30deg S30E0.png Topographic30deg S30E30.png Topographic30deg S30E60.png Topographic30deg S30E90.png Topographic30deg S30E120.png Topographic30deg S30E150.png
Topographic30deg S60W150.png Topographic30deg S60W120.png Topographic30deg S60W90.png Topographic30deg S60W60.png Topographic30deg S60W30.png Topographic30deg S60W0.png Topographic30deg S60E0.png Topographic30deg S60E30.png Topographic30deg S60E60.png Topographic30deg S60E90.png Topographic30deg S60E120.png Topographic30deg S60E150.png
Each tile is available at a resolution of 1800 × 1800 pixels (approximate file size 1 MB, 60 pixels = 1 degree, 1 pixel = 1 minute)
Processed LiDAR point cloud showing not only elevation, but heights of features as well. Airborne Lidar Bathymetric Technology.jpg
Processed LiDAR point cloud showing not only elevation, but heights of features as well.

See also

Related Research Articles

Fourteener Wikimedia list article

In the mountaineering parlance of the Western United States, a fourteener is a mountain peak with an elevation of at least 14,000 feet. There are 96 fourteeners in the United States, all west of the Mississippi River. Colorado has the most (53) of any single state; Alaska is in second place with 29. Many peak baggers try to climb all fourteeners in the contiguous United States, one particular state, or another region.

Sea Level Datum of 1929 vertical datum in the United States

The Sea Level Datum of 1929 was the vertical datum established for vertical control surveying in the United States of America by the General Adjustment of 1929. The datum was used to measure the elevation of a point above and depression below mean sea level (MSL).

North American Vertical Datum of 1988

The North American Vertical Datum of 1988 is the vertical datum for orthometric heights established for vertical control surveying in the United States of America based upon the General Adjustment of the North American Datum of 1988.

References

  1. Survey, U.S. Geological. "The National Map: Elevation". nationalmap.gov. Retrieved 2017-02-24.