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A graticule (from Latin crāticula 'grill/grating'), on a map, is a graphical depiction of a coordinate system as a grid of lines, each line representing a constant coordinate value. [1] It is thus a form of isoline , and is commonly found on maps of many kinds, at scales from local to global.
The World Geographic Reference System (GEOREF) is a geocode, a grid-based method of specifying locations on the surface of the Earth. GEOREF is essentially based on the geographic system of latitude and longitude , but using a simpler and more flexible notation .
An alphanumeric grid (also known as atlas grid [1]) is a simple coordinate system on a grid in which each cell is identified by a combination of a letter and a number. [2]An advantage over numeric coordinates such as easting and northing, which use two numbers instead of a number and a letter to refer to a grid cell, is that there can be no confusion over which coordinate refers to which ...
The grid lines point to a Grid North, varying slightly from True North. This variation is zero on the central meridian (north-south line) of the map, which is at two degrees west of the Prime Meridian, and greatest at the map edges. The difference between grid north and true north is very small and can be ignored for most navigation purposes.
Example: grid with coordinates (φ,λ,z) where z is the elevation. A standard Geoid surface. The z coordinate is zero for all grid, thus can be omitted, (φ,λ). Ancient standards, before 1687 (the Newton's Principia publication), used a "reference sphere"; in nowadays the Geoid is mathematically abstracted as reference ellipsoid.
For example, in the "1 Geohash digit grid" illustration of 32 rectangles, above, the spatial region of the code e (rectangle of greyish blue circle at position 4,3) is preserved with prefix e in the "2 digit grid" of 1024 rectangles (scale showing em and greyish green to blue circles at grid).
The Earth-centered, Earth-fixed coordinate system (acronym ECEF), also known as the geocentric coordinate system, is a cartesian spatial reference system that represents locations in the vicinity of the Earth (including its surface, interior, atmosphere, and surrounding outer space) as X, Y, and Z measurements from its center of mass.
For example, Albany, New York is roughly 140 miles north of New York City. Every site on Earth has a unique absolute location, which can be identified with a reference grid (such as latitude and longitude). Maps and globes can be used to find location and can also be used to convey other types of geographical information.