Glossary - Spatial Mathematics: Theory and Practice through Mapping - page 243

Nested hierarchy: A set of layers of polygons which fit neatly in association
with each other as one moves between layers.
Nested polygons: A system wherein smaller polygons fit together within larger
ones with no gaps and with no area spilling outside the larger ones.
Network analysis: The systematic study of geographical (or other) networks,
often using mathematics designed for the purpose.
Non-Euclidean geometry: Geometries that do not obey Euclid's Parallel
Postulate.
Normalizing data: In mapping, dividing one variable by another to create
ratio maps; for example, dividing population by state by total national
population in order to look at the ratio measure of population density.
Obelisk: A stone pillar, often a landmark, with a rectangular cross-section
and a pyramidal top.
Oblate spheroid: An ellipsoid generated by rotating an ellipse about one of
its axes such that the diameter of the equatorial circle is greater than
the length of the axis of revolution. The Earth is an oblate spheroid
with a polar axis shorter than its equatorial diameter.
Parallel: A small circle on the globe formed by a plane parallel to the equato-
rial plane.
Parallel Postulate (Euclid): In two-dimensional geometry, given a line m
and a point P not on m . There is exactly one line passing through P
that does not intersect m (is parallel to m ).
Partitioning of data: The separation of data into mutually exclusive and
exhaustive classes.
Perspective projection: In mapping, the projection of the globe to a surface
as seen through a single point.
Pixel/voxel: A pixel is a picture element—a basic unit on a computer screen.
A voxel is a 3D (volume) pixel.
Population potential: The accessibility of people from a given point—how
close people are to a point.
Precision: A measure of whether points taken within a system are close to
each other.
Prime number: A natural number that has exactly two natural number divi-
sors, itself and 1.
Projection: In mapping, the process of sending points on the globe to points
in the plane, thereby flattening the Earth's surface and allowing data
to be displayed in two dimensions on a paper or digital map.
Proximity: Nearness measured in terms of place, time, order, or other
concepts.
Public Land Survey System: Mathematically designed system as a nationally
conducted cadastral survey.
QR code: Quick Response code. A three-dimensional bar code.
Quantile: A method of data classification dividing the classes such that each
class contains the same number of observations.
Randomizing layer: In a dot density map, the layer in which the scatter of
dots is initially set forth.