G rid cell-A single discrete unit or square in a grid representing a portion of the Earth for example, a square meter or square mile. Grid bearing-See grid azimuth North, true. Although essentially a map quantity, a grid azimuth may, by mathematical processes, be transformed into a geodetic azimuth. G rid azimuth-At the point of observation, the angle in the plane of ‘ the projection measured between the central meridian of the plane coordinate projection system and a line containing the object sighted. The perspective grid is representative of a schematic network of coordinate grid lines on the ground or datum plane. Grid, perspective -A network of perspectively converging lines and their intersecting perpendicular lines drawn or superimposed by overlay on an oblique aerial photograph. Grid, parallactic -A uniform pattern of rectangular lines drawn or engraved on a transparent material, usually glass, and placed either over the photographs of a stereoscopic pair or in the optical system of a stereoscope to provide a continuous floating-mark system. These grids have been adopted by the United States and other NATO countries however, certain exceptions are allowed for previously established grids in foreign areas. Beyond the 80° parallels, the universal polar stereographic (UPS) grid is used. The universal transverse Mercator (UTM) grid is used on maps at scales of 1:250,000 and larger between 80° North and 80° South. Grid, military-A rectangular grid coordinate, or reference system placed on a map projection to facilitate the location and identification of map data for military purposes. 2 A system of points or lines for which field measurements are made, or for which computations are made to serve as a basic control system for measuring. The term is frequently used to designate a plane-rectangular coordinate system superimposed on a map projection, in which case it generally carries the name of the projection, i.e., Lambert grid, transverse Mercator grid, Universal transverse Mercator grid. The most common form of grid consists of uniformly spaced parallel lines intersecting at right angles. Grid- 1A network composed of two sets of lines, each set drawn according to a definite pattern and intersecting the other in a specific geometric arrangement.
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