- 行业: Earth science
- Number of terms: 93452
- Number of blossaries: 0
- Company Profile:
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 reading made at an instrument station in a level line and on a leveling rod standing on a bench mark or other point not in the continuous level line. In spirit leveling, there may be one or more extra foresights from a single instrument station or set up, but there can be only one backsight and one primary foresight from any one instrument station.
Industry:Earth science
A section of railroad track placed at the intersection of two rails and designed to provide support for the wheels and passageway for the flanges.
Industry:Earth science
The smallest solid angle resolvable by a scanner, expressed in radians.
Industry:Earth science
The product of the voltages of the intermediate frequency stages at two separate antennas receiving signals from the same celestial object, after passage through a low pass filter. The output has a sinusoidal variation because of the Earth's rotation with respect to the object. Each fringe has an amplitude proportional to the intensity of the source and a width proportional to a change of one wavelength between signals at the two antennas.
Industry:Earth science
The wall or rock under a vein or under other steeply inclined formation of minerals.
Industry:Earth science
That opening, in an optical system, which determines the largest angle for which principal rays from points in image space will pass entirely through the system. The field stop determines the field of view of the optical system; the aperture stop determines the brightness of the image.
Industry:Earth science
(1) The map on which are shown the lines along which an aircraft is to fly when aerial photographs are being taken, and/or the locations at which such photographs are to be taken. (2) The map on which have been plotted selected points at which aerial photographs were taken and the line of flight of the aircraft between those points.
Industry:Earth science
A force which, for purposes of computation or theory, can be considered to be a function only of the distance from a particular point; a force which is always directed toward a fixed point. Gravitational force is considered a central force in celestial mechanics except in those cases where the mass of one (or both) of the bodies involved is not uniformly distributed in spherical layers about a center and the two bodies are so close together that the asymmetric distribution of mass affects the orbits. For example, the Moon is so close to the Earth that the Earth's non-spherical shape appreciably affects the Moon's orbit.
Industry:Earth science
The device which holds the photographic film in the focal plane during exposure.
Industry:Earth science
The intersection of two or more lines of position not obtained simultaneously but adjusted to a common time.
Industry:Earth science
