- 行业: 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, ...
(1) An angle (f) formed by the intersection of segments of two great circles on a sphere. The two segments in the vicinity of the point of intersection are called the sides of the angle. The point itself is called the vertex of the angle. (2) A number expressing the rate at which the two sides of a spherical angle (f) diverge in the neighborhood of the vertex, and defined as the plane angle between the tangents to the two segments at the vertex.
Industry:Earth science
That part of astronomy which is concerned with the statistical distribution of the locations, motions, and other characteristics of stars and galaxies. It finds its subject matter both in positional astronomy and in astrophysics, and is very important to cosmology.
Industry:Earth science
Celestial mechanics applied to the motion of artificial satellites.
Industry:Earth science
The separation, by an optical or other system, of a single ray of polychromatic light in object space into distinct monochromatic rays in image space, without recombining them. In the absence of other kinds of optical aberration, chromatic aberration causes white light from a point in object space to focus into a continuous sequence of differently colored points in image space. Two kinds of chromatic aberration (c. A. ) are distinguished: longitudinal c. A. (also called axial c. A. ) and transverse c. A. also called lateral c. A. or off axis c. A. ). Longitudinal c. A. produces a sequence of differently colored points along a line parallel to the optical axis of the system. Transverse c. A. produces a similar sequence of points along a line perpendicular to the optical axis. Chromatic aberration can be overcome over a moderate range of wavelengths by using a lens system composed of optical elements having different dispersive powers. (An optical system made achromatic for visual observation is not strictly achromatic for photographic work. )
Industry:Earth science
The arc of the celestial equator, or the angle at the celestial pole, between the hour circle of the vernal equinox and the hour circle through the intersection of the celestial equator and the eastern celestial horizon at the instant a point on the oblique sphere rises. It is measured eastward from the hour circle of the vernal equinox through 24 hours.
Industry:Earth science
A side, of a triangulation network, which is measured with a JÄderin baseline apparatus or with a geodimeter type of instrument.
Industry:Earth science
A sheet of dimensionally stable material, upon which the graticule and ground control are plotted and upon which aero-triangulation or compilation is done.
Industry:Earth science
(1) Any coast and contiguous body of water which, for historical reasons, has become known as a bay.
(2) In international law, a bay over which there has been an exclusive assertion of sovereignty by a coastal nation, and an acquiescence by foreign (i.e., other) governments. It is sometimes required also that the bay have historically been known as such. Historic bays are well recognized exceptions to the rules applicable to ordinary bays and neither the semicircular rule nor the 10 mile limitation applies. Delaware and Chesapeake Bays are examples of historic bays in the United States of America.
Industry:Earth science
A point selected, in the overlap between a vertical photograph and its corresponding oblique photograph, about half way between the pass points.
Industry:Earth science
The axis, in a surveying instrument such as theodolite or leveling instrument, that is intended to be placed in a vertical position when the instrument is in use. This axis is also commonly called the vertical axis or, less frequently, the main axis or primary axis. However, the standing axis is never exactly vertical and may, in automatic leveling instruments, be more than a degree from the vertical while leveling. To call it the vertical axis can therefore be misleading.
Industry:Earth science
