- Industry: 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, ...
(1) The disappearance (obscuration) of one celestial body behind another of larger apparent size. (2) In particular, the disappearance of a star or planet because of the Moon has passed between it and the observer. The star or planet is said to be occulted. (3) The disappearance of a satellite behind the disk of its primary. If the primary source of illumination of a reflecting body is cut off by the occultation, the phenomenon is called an eclipse. The occultation of the Sun by the Moon is a solar eclipse. The differences between the three similar terms eclipse, occultation and transit are exemplified by the changes in the appearance of the moons of Jupiter. An eclipse occurs when a moon passes into the planet's shadow; an occultation occurs when the moon passes directly behind the planet, so that it could not be seen even if it were illuminated; and a transit occurs when the satellite passes between the observer and the planet, i.e., in front of the planet instead of behind it. Occultations of stars by the Moon have been timed as a means of determining the distances between the observing stations.
Industry:Earth science
A map projection producing a graticule bounded by a heart-shaped curve symmetrical about the central meridian, and representing parallels of latitude by arcs centered on the point representing a pole.
Industry:Earth science
An area equal to the area inclosed within a square one meter on a side.
Industry:Earth science
A test for the magnitude of the collimation error, carried out by leveling around a small loop which exaggerates the difference between backsight and foresight distances and produces a misclosure proportional to the collimation error of the leveling instrument.
Industry:Earth science
A condition equation requiring that the algebraic sum of the projections of the separate lines of a traverse upon perpendiculars to a fixed line (with which the traverse forms a closed figure) shall be zero. The perpendic-ular equation and the azimuth equation allow, when used together, the misclosure to be removed from a traverse which forms a loop with some fixed line such as a line of adjusted triangulation, by determining corrections to the measured angles of the traverse. The projections of the lines of the traverse upon lines which are perpendicular to a fixed line correspond to departures of those lines when the fixed line is considered the meridian of reference.
Industry:Earth science
Any stereoscopic model capable of being positioned so that the z-axis is parallel to the direction in which heights are measured in the model. Differences of z-coordinates are then the same as differences of height in the stereoscopic model and are proportional to differences of height in the original. The model is then said to be level. A model not capable of being made level is then said to be warped.
Industry:Earth science
Aerial photography in which distances between the taking camera and each of two or more points whose geodetic coordinates are known are determined simultaneously with the taking of the pictures. The distances have usually been determined using Shoran, Hiran or Shiran.
Industry:Earth science
