Glossary - Spatial Mathematics: Theory and Practice through Mapping - page 242

parts of equal moment about the line, or the arithmetic mean of all
points of the shape.
Geoid: A mathematically-computed surface of the Earth based on constant
gravity, used in computing absolute location on the Earth.
Geotagging: The process of adding spatial data (often coordinates) to a pho-
tograph or other media.
GIS: Geographic Information System—Software combining cartography, sta-
tistical analysis, and database technology to map data to enable users
to visualize spatial patterns. More broadly, GIScience, or Geographic
Information Science.
GPS: Global Positioning System—An accurate global navigational and sur-
veying system based on an array of satellites and the signals from
those satellites as received by on-the-ground devices.
Graph theory: Mathematics behind much network analysis; used to model
pairwise relations between elements of a given set. It is a founda-
tional branch of discrete mathematics.
Graticule: In mapping, a grid system, such as latitude-longitude, displayed
on a sphere.
Great circle: A circle formed by the intersection of the surface of a sphere
with a plane passing through the center of that sphere.
Hexagon: A six-sided polygon.
Hierarchy: In mathematics, an ordered set.
Hue: A color's direction from white in a color wheel.
Isoline: A line on a map joining points of equal value.
Join: In a GIS, to establish a relationship between a non-mapped table and
a map layer's attribute table. The relationship may be one-to-one or
many-to-one.
Jordan Curve Theorem: A topological theorem to systematically identify
inside and outside of simple closed curves. In mapping it has implica-
tions for digitizing and geocoding.
Latitude: An angular measure on the globe indicating distance North or
South of the Equator, often expressed in degrees and minutes.
Lattice: In mathematics, a partially-ordered set.
Longitude: An angular measure on the globe indicating distance East or
West of the Prime Meridian, often expressed in degrees and minutes.
Luminosity: The brightness of a color; how light or dark it is.
Manhattan space: Geometry that roughly parallels the pattern of the street
grid of Manhattan; geodesics are not unique.
Map: A representation of data in a spatial context.
Mean center: In geography, the point determined from the average x and y
values for a scatter of input points.
Meridian: A half of a great circle on the globe joining the North and South
poles.
Military Grid Reference System: A system to identify locations on the Earth
formed from two sets of parallel lines intersecting at right angles and
forming a grid of squares.