true horizontal plane
1Horizontal plane — In astronomy, geography, geometry and related sciences and contexts, a plane is said to be horizontal at a given point if it is locally perpendicular to the gradient of the gravity field, i.e., with the direction of the gravitational force (per… …
2True vertical depth — [http://www.glossary.oilfield.slb.com/Display.cfm?Term=true%20vertical%20depth] is the measurement of a straight line perpendicularly downwards from a horizontal plane.In the petroleum industry, true vertical depth, abbreviated as TVD, is the… …
3plane — 1. A two dimensional flat surface. See planum. 2. An imaginary surface formed by extension of a point through any axis or two definite points, in reference especially to craniometry and to pelvimetry. SYN: planum. [L. planus, flat] Addison …
4horizontal — Synonyms and related words: arrowlike, billiard table, bowling green, dead flat, dead level, dead straight, direct, earth, esplanade, even, flat, flatland, flattened, floor, flush, ground, homaloid, homaloidal, horizontal axis, horizontal fault,… …
5true horizon — 1. The boundary of a horizontal plane passing through a point of vision. 2. In photogrammetry, the boundary of a horizontal plane passing through the perspective center of a lens system …
6true horizon — i. The boundary of a horizontal plane passing through a point of the observer’s vision. ii. In photogrammetry, the boundary of a horizontal plane passing through the perspective center of a lens system …
7Horizontal coordinate system — The horizontal coordinate system is a celestial coordinate system that uses the observer s local horizon as the fundamental plane. This conveniently divides the sky into the upper hemisphere that you can see, and the lower hemisphere that you… …
8plane — I n 1. level surface, level, flat surface, flat; horizon, skyline, Astron., Navig. azimuth; sea level, water level; table, homaloid; plain, flatland, champaign, plateau, steppe, prairie; bowling alley, bowling green, pool or billiard table,… …
9Compass plane — Compass Com pass (k[u^]m pas), n. [F. compas, fr. LL. compassus circle, prop., a stepping together; com + passus pace, step. See {Pace}, {Pass}.] 1. A passing round; circuit; circuitous course. [1913 Webster] They fetched a compass of seven day s …
10Sundial — A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style (a thin rod or a sharp, straight edge) onto a flat surface marked with lines indicating… …
