- المجال: 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 method of determining details of the terrain, in a topographic survey, by locating those points (controlling points) of the terrain at which there are significant changes in the contours or direction of the contours. The relative elevations and planimetric coordinates of these points are then determined by survey, and the contours drawn by logical contouring. The controlling point method is extremely efficient, since it requires surveying to fewer points than does any other method. However, considerable experience is required of the surveyor to identify the controlling points.
Industry:Earth science
A scale indicating the relationship between two different units of measurement. e.g., meters to feet.
Industry:Earth science
A selective reducing agent, reducing those silver ions in silver halides in exposed regions of a photograph to metallic silver much more rapidly than it reduces the ions in unexposed parts.
Industry:Earth science
The statistical study of human populations, particularly with reference to size, constitution, density and distribution.
Industry:Earth science
A deed in which the grantor warrants the title against defects arising at any time either before or after the grantor became connected with the land.
Industry:Earth science
(1) The condition whereby objects in a plane perpendicular to the optical axis are imaged in a curved or dish shaped surface. Equivalently, an aberration affecting the longitudinal position of images off the axis so that objects in a plane perpendicular to the axis are imaged on a curved surface. Some telescopes used in astronomy and geodesy have pronounced curvature of field. This is particularly true of Schmidt telescopes, in which the focal surface is spherical and photographic film must be cut in the form of a Maltese cross in order to lie flat on the surface. (2) The distance, parallel to the optical axis, from an off axis image point to the plane through an on axis image point and perpendicular to the optical axis.
Industry:Earth science
The average value of the two principal curvatures of a surface.
Industry:Earth science
A rectangular Cartesian coordinate system in three dimensions which has the positive directions on the three axes (x-, y-, z-axes) defined in such a way that if the thumb of the right hand is imagined to point in the positive direction of the z-axis and the fore finger in the positive direction of the x-axis, then the middle finger, extended at right angles to the thumb and forefinger, will point in the positive direction of the y-axis. If the coordinate system is left handed, the middle finger will point in the negative direction of the y-axis. While two oppositely oriented, rectangular Cartesian coordinate systems can be defined on a plane, neither is intrinsically right handed or left handed. However, if the plane has a positive and negative side defined, then a z-axis with positive and negative directions could be considered present implicitly and right handed and left handed coordinate systems could be defined on the plane.
Industry:Earth science
The vertical distance (i.e., distance measured along a vertical) of a point above or below a surface of reference (datum). The vertical coordinate of a point may be positive or negative, depending on whether the point is above or below the surface of reference. This surface may be assigned a large positive value so that all vertical coordinates referred to it will be positive. The terms elevation and height are often used for vertical coordinate. The term elevations is best reserved, however, for vertical coordinates with respect to the geoid. The term height is best reserved for distance measured along a perpendicular, e. G. , geodetic height.
Industry:Earth science
A cone or ring formed around the vent through which materials from below the Earth's surface are ejected.
Industry:Earth science
