- 行业: Earth science
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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, ...
The conjunction of a planet whose orbit lies within the Earth's, when the planet is on the opposite side of the Sun from the Earth. Usually referred to simply as superior conjunction.
Industry:Earth science
A line drawn on a photograph to indicate where the photograph should be cut or torn for best matching it to the adjacent photographs in a mosaic.
Industry:Earth science
One of the three coordinates of a point in a three dimensional coordinate system.
Industry:Earth science
(1) One of two coordinates (r<sub>1</sub>, r<sub>2</sub>) of a point in the plane, indicating the distances of that point from two given, fixed points in the plane. The coordinates do not give a unique location for the point. To each point with a given pair of bipolar coordinates, there corresponds a second point on the other side of the line joining the two fixed points and an equal distance from that line. Hence a convention is needed to distinguish between the two locations. Bipolar coordinates are often used in electrostatic theory. They are also used in defining Nicolosi's map projection. (2) One of three coordinates (β<sub>1</sub>, β<sub>2</sub>, β<sub>3</sub>) related to rectangular, Cartesian coordinates (x,y,z) through the equations x = a sinh β<sub>2</sub> / (cosh β<sub>2</sub> - cos β<sub>1</sub>), y = a sin β<sub>1</sub>/ (cosh β<sub>2</sub> - cos β<sub>1</sub>) and z = β<sub>3</sub>, where a is a constant (length).
Industry:Earth science
A deed which is not properly recorded in a registry of deeds or other depository of public records. An unrecorded deed is binding on the grantor, his heirs and devisees, and on all other persons having actual notice thereof, but is not valid and effectual against any other persons.
Industry:Earth science
The angle, at a point P on the Earth's surface, between the theoretical direction of the vertical (opposite to the direction of gravity) and the actual direction of the vertical.
Industry:Earth science
(1) One of a set of three coordinates, of a point, in a geocentric coordinate system. The coordinates are commonly represented by (λ, φ', r) where λ, the longitude, is the angle from a reference plane through the polar axis to the plane containing the polar axis and the point; λ', the geocentric latitude, is the angle from the equatorial plane to the radius vector to the point; and r, the geocentric distance or geocentric radius, is the distance of the point from the center. The letter Ψ is frequently used instead of φ'. Note that the origin (intersection of polar axis and equatorial plane, or center of reference ellipsoid if one is used) need not be at the Earth's center of mass or geometric center. The complete set of three geocentric coordinates is also called a geocentric position. (2) One of a set of coordinates designating the location of a point by means of (a) the angle from the plane of the celestial equator to a line from the center of the Earth to the point and (b) the angle from the plane of a selected, initial geodetic meridian to that line. The first angle is called the geocentric latitude. The term geocentric longitude is not used for the second angle because that angle is the same as the geodetic longitude. This definition properly applies only to the exceptional case where the plane of the equator passes through the center of the Earth and the polar axis of the reference ellipsoid coincides with the Earth's polar axis. (3) The longitude and latitude of a point (on the Earth's surface) relative to the center of the Earth. The Earth's center of mass is usually meant.
Industry:Earth science
A formula for the reverse azimuth A <sub>21</sub> from point P<sub>2</sub> on a spheroid (rotational ellipsoid) to point P<sub>1</sub> on that spheroid, in terms of the forward azimuth A<sub>12</sub> from P<sub>1</sub> to P<sub>2</sub> and the forward and back azimuths B<sub>12</sub> and B<sub>21</sub> of points P<sub>1</sub>' and P<sub>2</sub>' on a sphere. Points P<sub>1</sub> and P<sub>1</sub>' have the same coordinates (λ<sub>1</sub>,φ<sub>1</sub>) and points P<sub>2</sub> and P<sub>2</sub>' have the same coordinates (λ<sub>2</sub>, φ<sub>2</sub>) ; λ and φ denote longitude and latitude, respectively. The formula is A <sub>21</sub> = A<sub>12</sub> + (B<sub>21</sub> - B<sub>12</sub>) - (e<sub>4</sub>/4) ( λ<sub>2</sub> - λ<sub>1</sub>)(φ<sub>2</sub> - φ<sub>1</sub>)² cos4φ<sub>1</sub> sinφ<sub>1</sub>, where e is the eccentricity.
Industry:Earth science
One of two angles, right ascension (α) and declination (δ), in an equatorial coordinate system.
Industry:Earth science
(1) A transparent sheet carrying a pattern of fine, gray or magenta, vignetted dots of different densities. It is used to produce a half-tone negative by contact-printing. (2) A half-tone screen made on a film and used in direct contact with another film to make a half tone image from a continuous tone original. (3) A patterned image on a film used in contact with another film or photographic plate to obtain a patterned image from an open window negative.
Industry:Earth science
