- 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, ...
The detection, in image space, of the image of the edge or line of an object in object space. This is a special kind of line detection.
Industry:Earth science
The darkening of unexposed photographic film by light leaking between the flanges of the spool on which the film is wound.
Industry:Earth science
The sensitometric density of the photo-graphic image of a sharply defined edge (knife edge), as a function of distance from a line parallel to the theoretical position of the image of the edge.
Industry:Earth science
The lengthening of a pendulum period by an electrostatic charge on the pendulum. A non metallic pendulum such as one made of quartz picks up an electro-static charge. This results in a change in the period, but can be prevented by placing a small amount of radioactive material in the container to ionize the gas and so let the charge leak off.
Industry:Earth science
An elevation determined by measuring atmospheric pressure with a barometer. The scale of atmospheric pressures indicated by the barometer can be calibrated to give altitude above some surface at standard pressure. This altitude (barometric altitude) must then be corrected for the elevation of the standard pressure surface above the geoid. The term is sometimes applied in error to the barometric altitude.
Industry:Earth science
An ellipsoid such that 50% of the points in a set of points having a Gaussian distribution in three dimensional space lie within the ellipsoid.
Industry:Earth science
A chain 100 feet long and composed of 100 links each 1 foot long. At the end of every 10th link, a brass tag is fastened notched to show the number of preceding 10 link segments.
Industry:Earth science
Measurement of the azimuths of three or more stars at the instants these stars pass through a circle of specified, constant angular elevation θ, and calculation of a correction Δσ to the assumed latitude σ, according to the equation ΔA <sub>o</sub> = δ <sub>A</sub> sec θ <sub>o</sub> cosec σ <sub>o</sub> cos τΔσ sec θ <sub>o</sub> cot σ <sub>o</sub> Δθ, in which ΔA<sub>o</sub> is the difference between observed and calculated values of a star's azimuth, δ A is a correction to readings on the horizontal circle, θ <sub>o</sub> is the assumed angular elevation, Δθ is the correction to the angular elevation, σ <sub>o</sub> is the calculated parallactic angle and τ is the calculated hour angle of the star. (There is one such equation for each observation).
Industry:Earth science
(1) A point, line, surface, solid or hyper solid which exists as an undefined part, postulate or geometrical theory. (2) A point, line, surface or solid, or a combination of these, which is the geometrical counterpart or representation of a physical object.
Industry:Earth science
The shape that the Earth would assume if it were entirely covered by a tideless ocean of constant depth. This definition is incomplete. It does not specify that the ocean be also without winds or currents, and does not specify how solid materials such as land formerly above water is to be redistributed.
Industry:Earth science
