altitude datum的意思|示意

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Altitude datum is an important concept in aerial photography and survey. It is the reference level used as the basis for measuring the elevation of a point. In aerial photography and surveying, the measurement of a point's elevation relative to the sea level, which is used as the altitude datum, is known as a height reading.

In aerial photography and surveying, altitude datum is used to establish the relative elevations of different points of the mapped area. For example, in flood risk mapping, the altitude datum is used to determine the height of the different points relative to sea level, which can then be used to identify areas at risk of flooding. The most commonly used altitude datum is mean sea level.

In addition, different types of altitude datum are also used for different surveys. For example, a topographic survey uses a vertical datum, which is a reference system for measuring the elevation of points relative to the ground surface. Other types of altitude datum include geoid, geoidal, and ellipsoid. In general, the altitude datum used depends on the type of survey being conducted.

Altitude datum is also important in establishing the vertical reference system of a map. For example, the US Geopotential Height Datum is used in the US Army Topographical Engineers to determine the elevation above sea level of a point on a map.

In conclusion, altitude datum is an important concept in aerial photography and survey, and is used to establish the relative elevations of different points of the mapped area. Different types of altitude datum are used for different surveys, and it is essential to choose the most suitable datum for the particular survey. Altitude datum is also important in establishing the vertical reference system of a map.