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Google Earth. Google Earth is a computer program that renders a 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposing satellite images, aerial photography, and GIS data onto a 3D globe, allowing users to see cities and landscapes from various angles. Users can explore the globe by entering ...
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. DEMs are used often in geographic information systems (GIS), and are the most common ...
The Shuttle Radar Topography Mission ( SRTM) is an international research effort that obtained digital elevation models on a near-global scale from 56°S to 60°N, [2] : 4820 to generate the most complete high-resolution digital topographic database of Earth prior to the release of the ASTER GDEM in 2009. SRTM consisted of a specially modified ...
Elevation. 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 ...
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 points of equal elevation), but historically using a variety of methods. Traditional definitions require a topographic map to show both ...
GTOPO30. GTOPO30 is a digital elevation model for the world, developed by United States Geological Survey (USGS). It has a 30- arc second resolution (approximately 1 km), [1] and is split into 33 tiles stored in the USGS DEM file format . According to DTED and USGS DEM the absolute vertical accuracy of GTOP30 varies from ±30 meters.
A geodetic datum or geodetic system (also: geodetic reference datum, geodetic reference system, or geodetic reference frame) is a global datum reference or reference frame for precisely representing the position of locations on Earth or other planetary bodies by means of geodetic coordinates. [1] Datums [note 1] are crucial to any technology or ...
They run from about 1,290 British pounds (about $1,900) for the smallest to six figures for the 50-inch Churchill model. He makes about 600 orbs a year of varying size, framing and ornamentation.