Chapter 7: Qualitative Thematic Maps
Thematic maps emphasize a single theme or a few related themes. Basic geographical reference information
will appear on a thematic map but the theme will stand out visually as the most important message of the map.
Thematic maps can show both qualitative and quantitative information. In chapter 8, we’ll see the methods
mapmakers use to portray quantitative information (information that portrays a magnitude message) such as
population density, annual rainfall.
In this chapter, we’ll see the ways mapmakers how qualitative information, or data that have classes varying in
type but not quantity. Examples include land cover, zoning, and soils.
Multivariate maps show the geographical relationships between two or more themes. Dynamic qualitative
thematic maps focus on changes in feature locations and attributes over time.
Qualitative information tells you only what different things exist—lakes, rivers, roads, cities etc.
Quantitative information consists of data giving you the magnitudes of things, such as how large,
wide, fast, or high they are.
A measurement level is a classification used to describe the nature of numerical info about features.
Nominal level information tells you simply which category (class) a feature belongs to. In GIS,
attributes carry the descriptive info for the geographic features.
Point feature information
Point feature is anything on the map, which is not a line feature, such as a small hill.
Data collection for point feature information: Point data are collected through image
interpretation using photographic and digital images, such as air photos or satellite images, to
identify objects and their attributes.
Linefeature is anything on the map, which can be followed, such as a path, stream or wall.
Data collection for line feature information: Like point feature data, line feature info is
commonly collected through a variety of methods, including surveys, field observation and
Area feature information
Mapmakers commonly use twodimensional area features to divide a region into areas that have
some common qualitative attribute. The idea here is that qualitative features within a category
share some common traits, while differing significantly from the other categories.
Data collection for area feature information: Area feature data collected by ground survey, image
interpretation, or other methods such as census taking to determine the category for each data
collection area. Homogeneity
Homogeneous means uniform in structure or composition throughout. For instance, a stand of trees
might prove to be entirely of the same species. The stand is a completely homogeneous qualitative area
feature since all of its defining objects (trees) are of the same