- 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 net increase, in distance or area per photograph, in the direction of flight for a specified amount of overlap. Commonly abbreviated as GGF. It is used to compute the number of exposures in a strip of aerial photographs.
Industry:Earth science
An entry initiated under the homestead laws and providing for the entrance of patents to entrymen who settle upon and improve agricultural land.
Industry:Earth science
That building, at the Geodetic Institute in Potsdam, at which definitive measurements of gravity have been made and which for many years was the reference point for gravity networks.
Industry:Earth science
A survey made on the ground and not by an aerial survey. A ground survey provides coordinates of points on the ground, distances between points on the ground, or angles between points on the ground, or any combination of these quantities. It is used to provide ground control to which photogrammetrically determined coordinates can be adjusted. It may or may not use photographs.
Industry:Earth science
Near the direction of the Sun, first becoming visible just before sunrise or just after sunset, and then setting. Said of a star whose direction is near that of the Sun.
Industry:Earth science
A photograph of the horizon, taken simultaneously with a vertical photograph to obtain an indication of the tilt of the vertical camera at the instant of exposure.
Industry:Earth science
(1) The gravity correction δg <sub>f</sub> ≡ Σ (hn/n!)(δnτ/δhn) giving the change in gravity found in going from a point Q on the reference surface to the point P on the normal through Q. H is the distance QP and τ is the value of gravity calculated for Q. The first two terms are, explicitly, -2 τh/(R+h) and +3 τh²/(R+h)². R is the radius of the Earth at Q. If P is at an elevation of less than 2 km, terms of degree two and higher are not needed. δg <sub>f</sub> is then approximately -τh/R, or -0.3086 h mgal (or newtons/kg, etc.). The free air gravity correction is sometimes undesirably referred to as Faye's gravity correction. (2) The same as the preceding definition, but with g, the actual value of gravity at P, used instead of τ and H, the elevation of P, used instead of h. This definition has been used when two theoretical values of gravity acceleration were being compared. A theoretical value gravity acceleration was calculated for Q from a measured value at P and compared with a value calculated for Q from a gravity formula.
Industry:Earth science
A pole divided at heights above top of floor or top of window sills to top of next floor etc., and used to give the heights of various points in a wall of masonry.
Industry:Earth science
The force of gravity acting on a portion of atmosphere, reduced by the amount of the centrifugal force caused by motion of that portion relative to the lithosphere.
Industry:Earth science
The ratio of the amount (mass or weight) of water present in a given volume of air, at a given temperature, to the greatest amount possible at that temperature.
Industry:Earth science
