- Industria: 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) The vertical angle, at the point of observation, between the true horizon and a line of sight to the apparent horizon. The true horizon is the horizontal plane passing through the point of observation. (2) The vertical angle, at an air station, between the true horizon and the apparent horizon, which results from refraction, curvature of the Earth and flight height.
Industry:Earth science
(1) The angle between two directions. It is numerically equal to the value of the angle between two lines extending in the given directions. Astronomers frequently refer to angular distance merely as distance.
Industry:Earth science
The sum of the separate discrepancies which occur in the various steps of making a survey or of computing the results of a survey. For example, if two level lines, run independently over the same set of bench marks, are computed separately, differences between the two sets of elevations will accumulate. This does not mean that the accumulated discrepancy will necessarily increase in magnitude.
Industry:Earth science
Distance from a specified point which is, usually, in motion.
Industry:Earth science
A digit which is a member of the set of eight digits 0,1,2,3,4,5,6,7 used in the number system having the radix 8.
Industry:Earth science
Horizontal direction expressed as an angle from magnetic north.
Industry:Earth science
Length measured in terms of the distance traveled by radio waves in unit time.
Industry:Earth science
(1) In surveying and mapping, the angle between a line or plane and an arbitrarily chosen reference line or plane. At a triangulation station, observed horizontal angles are referred to a common reference line and termed horizontal direction. They are usually collected into a single list of directions, with the direction of 0„a placed first and the other directions arranged in order of increase clockwise. (2) A line, real or imaginary, pointing away from some specified point or locality toward another point. Direction has two meanings: that of a numerical value and that of a pointing line. Two lines must be specified for the first definition to be valid; only one line need be specified for the second meaning. (3) An indication of the location of one point with respect to another without involving the distance between the two points. It is usually thought of as a short segment (of a straight line between the two points) having one end at one of the points and having an arrow like symbol at the other end. Note that a direction is not an angle.
Industry:Earth science
The radial distortion characteristic of a particular camera.
Industry:Earth science
(1) The function δ (x - x<sub>o</sub>), which has the value 0 for all values of x other than x<sub>o</sub> and has the value 1 at x<sub>o</sub>. (2) The function δ(x - x<sub>o</sub>) such that <br>
Industry:Earth science
