Most published and online maps fall into four categories:
Navigation maps, including topographic maps and nautical and aeronautical charts
Geophysical maps, that show the structure and dynamics of earth, oceans and atmosphere
Location maps, that depict the locations and names of physical features
Thematic maps, that portray attribute data about locations and features
Although online maps often combine these categories in new and unexpected ways, published maps and atlases tend to respect them.
Thematic maps tend to be more highly stylized than other types of maps and frequently omit locational information such as place names, physical features, coordinate grids, and map scales. This is because rather than showing physical features on the ground, such as shorelines, roads, settlements, topography, and vegetation, a thematic map displays quantified facts (a "theme"), such as statistics for a region or sets of regions. Examples include the locations of traffic accidents in a city, or election results by state. Thematic maps have a wide vocabulary of cartographic symbols, such as point symbols, dot distributions, "quiver" vectors, isolines, colored zones, raised prisms, and continuous 3-D surfaces. Mapping Toolbox™ functions, listed in the following table, can generate most of these types of map symbology.
Plots directed vectors in 2-D from specified latitudes and longitudes with lengths also specified as latitudes and longitudes
Plots directed vectors in 3-D from specified latitudes, longitudes, and altitudes with lengths also specified as latitudes and longitudes and altitudes
Draws fixed or proportional symbol maps for each point in a vector
with specified marker symbol. Similar maps can be generated using
Projects a 3-D stem plot map on the current map axes. The
|Calculates and displays Tissot Indicatrices, which graphically portray the shape distortions of any map projection.|
The most familiar form of thematic map is probably the choropleth map (from the Greek choros, for place, and plethos, for magnitude). Choropleth maps use colors or patterns to represent attributes associated with certain geographic regions. For example, the global distribution of malaria-carrying mosquitoes can be illustrated in a choropleth map, with the habitat of each mosquito represented by a different color. In this example, colors are used to represent nominal data; the categories of mosquitoes have no inherent ranking. If the data is ordinal, rather than nominal, the map may contain a colorbar with shades of colors representing the ranking. For instance, a map of crime rates in different areas could show high crime areas in red, lower crime areas in pink, and lowest crime areas in white. See Create Choropleth Map of Population Density for an example of creating a choropleth map where the color of each location indicates the population density.
To create a choropleth map with the Mapping Toolbox:
Stem plots are 3-D geographic bar graphs portraying numeric attributes at point locations, usually on vector base maps. Below is an example of a stem plot over a map of the continental United States. The bars could represent anything from selected city populations to the number of units of a product purchased at each location:
Contour and quiver plots can be useful in analyzing matrix data. In the following example, contour elevation lines have been drawn over a topographical map of the Gulf of Mexico. Quiver plots have been added to visualize the gradient of the topographical matrix.
Here is the displayed map:
scatterm function plots symbols at specified point
locations, like the MATLAB®
scatter function. If the symbols are small and inconspicuous
and do not vary in size, the result is a dot-distribution map.
If the symbols vary in size and/or shape according to a vector of attribute values,
the result is a proportional symbol map.