Glossary
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Tesselation data model
A geographic data model where the basic logical unit is a location
in space shown by a single cell or polygon in a mesh usually represented
or classified as a regular grid or rectangular pixel; however, it
can be represented by an infinitely repeatable pattern of a regular
polygon or polyhedron. It can also be classified as hierarchical or
as irregular. The presence of specific entities are recorded as descriptors
of each location.
Thematic map
A map that displays the spatial distribution of an attribute that
relates to a single topic, theme, or subject of discourse. Usually,
a thematic map displays a single attribute (a "univariate map")
such as soil type, vegetation, geology, land use, or landownership.
For attributes such as soil type or land use ("nominal"
variables), shaded maps that highlight regions ("polygons")
by employing different colors or patterns are generally wanted. For
other attributes (like population density - a "metric" variable),
a shaded map in which each shade corresponds to a range of population
densities is generally wanted. Thematic maps are used to display geographical
concepts such as density, distribution, relative magnitudes, gradients,
spatial relationships and movements. Also called geographic, special
purpose, distribution, parametric, or planimetric maps.
Topographic map
A map depicting terrain relief showing ground elevation, usually through
either contour lines or spot elevations. The map represents the horizontal
and vertical positions of the features represented. It is a graphic
representation delineating natural and man-made features of an area
or region in a way that shows their relative positions and elevations.
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