Glossary - Spatial Mathematics: Theory and Practice through Mapping - page 244

Raster format: A data structure composed of a rectangular grid of pixels.
Reference ellipsoid: A mathematically-defined shape that is a “best-fit” to
the geoid, most often for a continent, but potentially for the entire
globe. Smoother than the geoid, it is the surface upon which coordi-
nate systems are defined.
Regular/irregular data pattern: The evaluation of pattern that invokes con-
cepts such as symmetry or its lack thereof.
Relative location: Referencing positions on the Earth by indicating displace-
ment from another location or site, which may include terms such as
near, adjacent, left, or ahead.
Remote Sensing: The science of acquiring and interpreting imagery col-
lected from indirect recording of a specific band or bands of energy
reflected from the Earth, such as satellite imagery.
Representative fraction: A fraction expressing map scale that is indepen-
dent of units.
Resolution: Sharpness or level of detail in an image. It is directly related to
the number and density of pixels.
RGB/CMYK: Color models by which all colors are described as a mixture of
base colors. RGB—Red, Green, Blue; CMYK—Cyan, Magenta, Yellow,
and Black.
Routing: The planning of a line through a set of points (route) through real
or imaginary locations.
Saturation: The degree to which a color is intense or concentrated.
Scale: A numerical relationship, expressed as a ratio, between the actual size
of an object and the size of an image that represents it on a map, plan,
or diagram. A map scale is an expression of how many units on the
map represent a corresponding number of units on the Earth's sur-
face. The manner of expression may take various forms.
Set intersection/union: The intersection of sets A and B is composed of all
elements simultaneously in both sets and no other elements. Union of
sets A and B is all elements in A together with all elements of B—in
A or B or both.
Shaded relief: Hill shading or coloring to simulate the shadow on a raised
relief map.
Small circle: A circle formed by the intersection of the surface of a sphere
with a plane intersecting the sphere at more than a single point but
not passing through the center of the sphere.
Spatial Analysis: With GIS, analyzing geographic phenomena in terms of
their distribution on a map. It might involve mapping elements of
slope and aspect, attributes, connection and network patterns, hydro-
logical models, overlays, geocoding, and others.
Spider diagrams: Conceptual visualizations of regions and connections
between regions.
Standard deviational ellipse: An area representing one standard deviation
from the mean center of all the data in a data set. It measures whether