Cartography is about maps. This includes the art, science, and technology of
map making, the use of maps as research tools and as sources of information,
and the study of maps as historical documents and works of art.
Cartography has always been closely associated with Geography and Surveying.
Its recognition as a distinct discipline is relatively recent. Scientific
journals dealing with Cartography began to appear in the middle of the
twentieth century. Numerous definitions of Cartography have appeared in the
literature. Earlier definitions tend to emphasize map making while more
recent definitions also include map use within the scope of Cartography.
The traditional view of Cartography focused on map making and implicitly
assumed that if you knew how to make a map, then you also knew how to use
maps. This assumption was legitimate when the map maker was also the map
user, e.g. a geographer making maps of data collected through field work
as part of her data analysis. In this context, the map user was familiar
with the data represented on the map, was aware of the limitations of the
data and the mapping techniques employed, and could therefore be expected
to use the map effectively for its intended purpose. However, this context
is not typical of most uses of maps.
More often than not, the map user is different from the map maker and the
map maker rarely collects the original data. Recognition of this has led
to a redefinition of Cartography which is based in part on work by
communications theorists. In this context, Cartography is viewed as being
concerned with a particular form of communications process which relies on
graphic images, i.e. maps, to convey information about data and the spatial
relationships between them, e.g. a geographic environment. The cartographer
is the map maker. The map is the communications medium. The data may be
about towns, temperatures, bedrock, people, crops, water depths, algae
growth patterns, the stars, or even about cellular structure, neural
networks, or DNA. The map represents the spatial relationships among the
individual pieces of data. The map user "reads" the map and interprets its
information content in the context of his or her own objectives and
knowledge of the environment or spatial pattern which the map describes.
Some major terms within the cartographic environment are: map projection,
map datums, and map coordinates. Projection is the method in which the map
maker uses to display or project a spherical object's (earth) spatial data
into a plane surface (2d map). Imagine projection being the method you would
use if you had to slice a basketball in certain places to make it lay flat
on the ground with all outside walls showing. Coordinates are imaginary
lines on the earth which a map user uses to define and locate a specific
point on the earth. A map datum is a method in which the coordinates are
layed out on the earth. Since the earth is not perfectly round, two points
on a map may differ in real distance than two other points somewhere else
on the map although they are the same on paper. A datum is a method used to
minimize these differences.