- Industry: Earth science
- Number of terms: 93452
- Number of blossaries: 0
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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, ...
Related by lying in pairs on straight lines through a given point. Two sets of points are said to be in perspective from a given point if corresponding points in the two sets lie on a straight line passing through the given point.
Industry:Earth science
That branch of surveying in which the surface chosen to represent the Earth's surface locally is a plane. In plane surveying, the Earth's curvature is ignored and the formulas of plane geometry and plane trigonometry are used in the computations. In general, plane surveying is used in surveying regions and boundaries whose greatest dimension is less than 150 km or where the accuracy required is so low that corrections for the effect of curvature would be negligible in comparison to the errors of measurement. For regions of small extent, accurate results can be obtained with the methods of plane surveying, but the accuracy and precision of such results will decrease as the region increases in size.
Industry:Earth science
Any difference in the diameters, or any irregularities in the form, of the pivots of the horizontal axis of a surveying or astronomical instrument (telescope). A pivot inequality causes a pivot error. Formerly, corrections for pivot inequality were made to astronomical measurements taken for geodetic surveys. Such corrections are not needed for measurements made with precise, modern instruments.
Industry:Earth science
A figure having four sides, opposite sides being parallel to each other. Opposite sides are also equal in length and opposite angles are equal in magnitude. The line joining opposite vertices (the points in which sides join) are called diagonals. The area of a parallelogram is equal to the product of the length of one side by the perpendicular distance to the opposite side.
Industry:Earth science
A self-reading leveling-rod on which the graduations are marked by rows of alternately circular and diamond shaped dots running diagonally across the rod. This leveling rod is no longer in general use.
Industry:Earth science
(1) Photogrammetry applied to determining the geometry of surfaces, as distinguished from photogrammetry applied to determining the geometry of figures on surfaces. I.e., photogrammetry applied to determining the coordinates of the surface in a three-dimensional coordinate system. (2) In particular, photogrammetry applied to mapping the surface of the Earth, or other celestial body. One of the coordinates is always height, either geodetic height or height in a rectangular, Cartesian coordinate system. However, this coordinate is usually converted to elevation when the photogrammetric data are used for making a map.
Industry:Earth science
(1) A plane parallel to the average position of the Earth's axis of rotation and containing the average position of the vertical at the observer. (2) A plane parallel to the average position of the Earth's axis of rotation and containing the vertical at that point on the geoid vertically below the observer.
Industry:Earth science
A linkage made of wooden or metallic bars and shaped like a parallelogram pinned at the corners; two opposite sides of the parallelogram are extended slightly beyond the corners and in opposite directions. The pantograph is used for copying pictures or diagrams at magnified or reduced scales. It also occurs as a component of other mechanisms.
Industry:Earth science
