- 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, ...
Photogrammetry applied to purposes other than mapping. Non topographic photogrammetry should not be confused with close-range photogrammetry, although the two terms are sometimes used as if they were synonyms.
Industry:Earth science
One of the times, designated New Moon, First Quarter, Full Moon and Last Quarter, at which the excess of the apparent celestial longitude of the Moon over that of the sun is 0<sup>o</sup>, 90<sup>o</sup>, 180<sup>o</sup> and 270<sup>o</sup> respectively.
Industry:Earth science
That term, in a formula for the value of gravity, explicitly containing the geodetic longitude ë and geodetic latitude ö as arguments and implying that the geoid is represented by an ellipsoid having three unequal axes. With this additional term (longitude term), the gravity formula would be written as τ<sub>o</sub> = τ<sub>e</sub> ((1 + β <sub>1</sub> sin²φ + β <sub>2</sub> sin²2φ + β <sub>3</sub> cos²φ cos 2(λ - λ <sub>o</sub>)), in which τ<sub>e</sub> is the average value of gravity at the equator and β <sub>3</sub>, like β <sub>1</sub> and β <sub>2</sub>, is a dimensionless number. As always the gravity formula implies a surface of definite shape; when the surface is an ellipsoid having three axes of different lengths, the shortest axis is the polar axis, corresponding to the Earth's rotational axis, while the two longer axes lie in the equatorial plane. The longest axis lies in the plane at longitudes λ <sub>o</sub> and λ <sub>o</sub> ± 180<sup>o</sup>. The two equatorial axes differ in length by 4aβ <sub>3</sub>, in which a is the length of the longer semi-major axis. The idea of representing the Earth by an ellipsoidal body having axes of three unequal lengths is by no means new. There was, however, no continuing interest in the idea until Helmert and his assistant, Berroth, each published in 1915 his calculations on which were based gravity formulae containing a longitude term of the type given above. Since 1915, various discussions of the accumulating amount of data on gravity have tended to confirm the belief that the geoid is closely approximated by an ellipsoid having a size and character like that proposed by Helmert. Studies of the deflection of the vertical have likewise tended to confirm that belief. But such a surface is not likely to be used as a reference surface for geodetic networks, maps or deflections of the vertical. The mathematical complications are two great. Also, it is convenient to use the same reference surface for both gravity and deflections of the vertical and therefore to omit the longitude term from the gravity formula. Besides Helmert's formula, a number of other gravity formulae have contained a longitude term. The values are given, in the table below, for the constants in some of these formulae. <br>
Industry:Earth science
A value (distance) assigned the east-west line on a map grid to avoid the inconvenience of using negative northings to some points. Equivalently, a constant value added to the northing of points on a map grid with origin at (0,0).
Industry:Earth science
The establishment, on the ground, of points and lines in locations previously determined by computation or graphical methods. The plans for an engineering project (road, canal, etc.) are prepared in the office from survey data obtained in the field. These plans form a paper location and are the basis for the location survey.
Industry:Earth science
The equation x x' = f f', in which x is the distance, in object-space, of an axial-point from the front focal point; f is the distance, in object-space, of the front focal-point from the center of the lens; x' and f' are the corresponding distances, in image-space, of the corresponding axial point and back focal-point.
Industry:Earth science
Observations or measurements made simultaneously from several different points.
Industry:Earth science
An owner or occupant whose property adjoins or touches other land.
Industry:Earth science
