- 行业: 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, ...
A camera system which allows photographs to be taken of an object from different viewpoints even though camera and object occupy fixed positions. The system consists of a camera, a tiltable easel on which is mounted the object to be photographed, and, between the camera and the easel, a spherical mirror of large diameter to provide a variable perspective. A flat secondary mirror is often added to lengthen the optical path. Such a camera system can be used for rectifying highly oblique photographs or for making images with arbitrary perspective from vertical photographs or from maps.
Industry:Earth science
(1) A square, or a portion of a city or town inclosed by streets but not containing any streets. (2) A subdivision of a town site. (3) The platted portion of a city, surrounded by streets. The term need not be limited to blocks platted as such but may designate a region bounded on all sides by streets or avenues. It must be surrounded on at least three sides by streets which must be marked on the ground and not simply indicated on a plat. (4) Two or more strips of overlapping photographs.
Industry:Earth science
A nautical chart intended for coastwise navigation offshore. A general chart is of smaller scale than a coast chart but of larger scale than a sailing chart.
Industry:Earth science
(1) A device installed on certain aerial cameras to keep the image stationary on the focal plane while photographing objects on the ground. (2) A device installed or used in conjunction with a camera to keep the image stationary during exposure even though the camera is moving with respect to the object being imaged.
Industry:Earth science
A small circle on a sphere representing the Earth, at every point of which, at the instant of observation, the observed celestial body (Sun, star, planet) has the same angular elevation and therefore the same zenith distance. At the instant of observation, the center (on the sphere) of the circle of position is that point which has the same longitude and latitude as the celestial body. The radius of the circle is the observed zenith angle of the body. The point representing the observer is therefore somewhere on that circle. A second observation on the same object at a different time (or on a different object at the same time) will determine a second and different circle of position, and if the observer has not moved, his representing point will be at the intersection of these circles. If the observer has moved, as may occur if he is on a ship or aircraft, allowance is made for the direction and amount of movement and a location deter-mined for either point of observation. In navigation, a short portion of the circle of position is plotted as a straight line and termed a line of position or a Sumner line. A Sumner line, however, is merely a particular variety of line of position and the term should not be used as a synonym for line of position.
Industry:Earth science
The line connecting opposite quarter-section corners, or opposite sixteenth section (quarter quarter section) corners.
Industry:Earth science
A single color produced by subtracting from white light a mixture of colored lights.
Industry:Earth science
A photographic atlas of the whole sky, intended to show the locations of all stars of magnitude 13. 5 or less (about 3 - 4 million stars in all) and produced by international cooperation according to an agreement reached among astronomers in Paris in 1887. A number of observ-atories have telescopes designed particularly for this work, but the project is not complete.
Industry:Earth science
One of the auxiliary points established in using Collins' method or Cassini's method (of resection).
Industry:Earth science
