- Branche: Earth science
- Number of terms: 93452
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Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
The difference between the elevations of successive low tides.
Industry:Earth science
A formal, written instrument made between two or more persons. The term is derived from the ancient practice of indenting or cutting the deed in a waving line.
Industry:Earth science
An intersection designed for easy and safe transfer from one road to another, usually with the roads being placed at different levels at the intersection.
Industry:Earth science
A radio interferometer having the antennas connected directly (usually by cables) to the receiver.
Industry:Earth science
An optical effect - bright objects viewed against a dark background appear to be larger than they really are. This effect has a physical basis and is encountered in photographs of celestial objects as well as when viewing the objects directly. It should not be confused with the Moon paradox - an extended object such as the Moon, for example, appears larger when seen on the horizon than when seen high in the sky.
Industry:Earth science
A distance-measuring instrument entirely or almost entirely mechanical in nature. Examples are the odometer and the surveyor's tape. The former is a self-sufficient instrument; the latter must usually be used with additional devices such as pins, stakes, scales, etc. If the instrument is at all complex, or if it must be prepared or put together in the field, it is referred to as apparatus, e.g., base line apparatus.
Industry:Earth science
One of two methods devised by T. Banachiewics for solving a system of simultaneous linear equations; the first method corresponds closely to Gauss's method, the second to Cholesky's method.
Industry:Earth science
The formula τ = 978.049 (1 + 0.0052884 sin²φ - 0.0000059 sin²2φ), in which φ is the geodetic latitude. This is a development of the formula for gravity, based on the representation of the Earth by a body shaped like a rotational ellipsoid having the dimensions of the International Ellipsoid of reference (Madrid, 1924) and rotating about its minor axis one in a sidereal day, and on the assumptions that (a) the surface of the ellipsoid is a level surface and that (b) the value of gravity acceleration at the equator is 978.049 gals. The International Gravity Formula was adopted by the International Association of Geodesy at its meeting in Stockholm in 1930. The purpose was not, primarily, to represent the gravity measurements then avail-able, although the value 978.049 was based on those measurements, but rather it was intended to put the determination of the figure of the Earth from gravity data on the same basis as the determination of the figure of the Earth from deflections of the vertical. The formula is based on the Potsdam value for gravity. It has been replaced, for general used, by Gravity Formula 1967 and by later formulae, but is still used for some purposes.
Industry:Earth science
(1) The image of a definite point on the object. Because no optical system is perfect, a single point in object space gives rise to wave fronts which do not converge again to a single point but, at their smallest, still occupy an appreciable volume. The region in which this small volume is intersected by a focal surface is called an image patch. The image point can be a point in a virtual image. It is then (ideally) the point which is the common center of the diverging spherical waves in image space. (2) The image, on a photograph, corresponding to a definite point on the object.
Industry:Earth science
