Cartography: Thematic Map Design Download Pdf
Zoe Northcutt
Cartographers apply many design principles when compiling their maps and constructing page layouts. Five of the main design principles are legibility, visual contrast, figure-ground, hierarchical organization, and balance. Together these form a system for seeing and understanding the relative importance of the content in the map and on the page. Without these, map-based communication will fail. Together visual contrast and legibility provide the basis for seeing the contents on the map. Figure-ground, hierarchical organization, and balance lead the map reader through the contents to determine the importance of things and ultimately find patterns.
Visual contrast which relates to how map features and page elements contrast with each other and their background. To understand this principle at work, consider your inability to see well in a dark environment. Your eyes are not receiving much reflected light so there is little visual contrast between features and you cannot easily distinguish objects from one another or from their surroundings. Add more light and you are now able to contrast features from the background. This concept of visual contrast also applies in cartography (figure 1). A well-designed map with a high degree of visual contrast can result in a crisp, clean, sharp-looking map. The higher the contrast between features, the more something will stand out, usually the feature that is darker or brighter. Conversely, a map that has low visual contrast can be used to promote a more subtle impression. Features that have less contrast will appear to belong together.
Visual contrast and legibility are the basis for seeing. In addition to being able to distinguish features from one another and the background, the features need to be large enough to be seen and to be understood in order for your mind to decipher what you eyes are detecting. Visual contrast and legibility can also be used to promote the other design principles: figure-ground, hierarchical organization, and balance.
Together these five cartographic design principles have a significant impact on your map. How they are used will either draw the attention of your map readers or potentially repel them. Giving careful thought to the design of your maps using these principles will help you to assure that your maps are ones people will want to look at!
In March 1972, Dent published an article in the Annals of the Association of American Geographers entitled Visual Organization and Thematic Map Communication. In the article, he referenced studies that documented the misinterpretation of the information on thematic maps by map readers.
Cartographers apply many design principles when compiling their maps and constructing page layouts. Five of the main design principles are legibility, visual contrast, figure-ground organization, hierarchical organization, and balance. Together these principles form a system for seeing and understanding the relative importance of the content in the map and on the page. Without these, map-based communication will fail.
The concept of visual contrast also applies in cartography (Figure 1). A well-designed map with a high degree of visual contrast can result in a crisp, clean, sharp-looking map. The higher the contrast between features, the more some features will stand out (usually features that are darker or brighter). Conversely, a map that has low visual contrast can be used to promote a more subtle impression. Features that have less contrast appear to belong together.
Figure-ground organization is the spontaneous separation of the figure in the foreground from an amorphous background. Cartographers use this design principle to help map readers focus on a specific area of the map. There are many ways to promote figure-ground organization, such as adding detail to the map or using a whitewash, a drop shadow, or feathering.
Figure 4. When the symbols and labels are on the same visual plane (A), it is difficult for the map reader to distinguish among them and determine which are more important. For a general reference map (B), using different sizes for the text and symbols (e.g., city points and labels), different line styles (e.g., administrative boundaries), and different line widths (e.g., rivers) are some of the ways you can add hierarchy to the map. When mapping thematic data (C), the base information (e.g., county boundaries and county seats) should be kept to a minimum so that the theme (e.g., soils) is at the highest visual level in the hierarchy.
Thematic Maps are sometimes also called special purpose, single topic, or statistical maps. They highlight features, data, or concepts, and these data may be qualitative, quantitative, or both. Thematic maps can be further divided into two main categories: qualitative and quantitative. Qualitative thematic maps show the spatial extent of categorical, or nominal, data (e.g., soil type, land cover, political districts). Quantitative thematic maps, conversely, demonstrate the spatial patterns of numerical data (e.g., income, age, population).
Maps also are not limited to depicting outdoor landscapes. Some maps, such as the one in Figure 1.2.7, are designed to help people navigate complicated indoor spaces, such as malls, airports, hotels, and hospitals.
Though there are many different types of maps, they share the goal of demonstrating complex spatial information in a clear and useful way. Rather than attempt to place maps into discrete categories, it is generally more productive to see them as individual entities designed to suit a particular audience, medium, and purpose. We will discuss this more in the next section.
The purpose of the competition is to promote interest in map design and to recognize significant design advances in cartography. The focus of this competition is design; therefore, judging is based on cartographic design criteria, such as creativity, text (spelling and grammar, too), balance, unity, visual hierarchy, clarity, use of color, and subject matter.
Each student award consists of a cash prize ($500) and a copy of Avenza MAPublisher. Student mapmakers in a certificate, diploma, or degree program (bachelor, masters, doctorate) must have produced their entries with student facilities as part of an accredited course. Student entries must be verified via the instructor. All competition entries will become part of the permanent collection of the U.S. Library of Congress and winning entries will be displayed at a number of national and international professional functions. Digital images of winning entries will also be provided (with permission) to educators and teachers as examples of excellent map design for their students.
There are NO FEES for student entries.
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A thematic map is a specialized map made to visualize a particular subject or theme about a geographic area. Thematic maps can portray physical, social, political, cultural, economic, sociological, or any other aspects of a city, state, region, nation, continent, or the entire globe.[1] A thematic map is designed to serve a special purpose or to illustrate a particular subject, in contrast to a general map, on which a variety of phenomena appear together, such as landforms, lines of transportation, settlements, and political boundaries.[2] This is in direct contrast to a reference map or Topographic map, which are designed to show the location of visible features of the landscape with minimal interpretation and intended to be used for a wide variety of purposes. Thematic maps also portray basic features such as coastlines, boundaries and places, but they are only used as a point of locational reference for the phenomenon being mapped.[2]
Thematic maps also emphasize spatial variation of one or a number of geographic distributions. These distributions may be physical phenomena such as climate or human characteristics such as population density and health issues. Barbara Petchenik described the difference as "in place, about space."[3] While general reference maps show where something is in space, thematic maps tell a story about that place based on spatial patterns.[4] Thematic maps are sometimes referred to as graphic essays because they display spatial variations and interrelationships of geographical distributions that can be interpreted.
An important cartographic element preceding thematic mapping was the development of accurate base maps. Mapping accuracy improved at a gradual pace, and even until the mid-17th century, general maps were usually poor quality. Still, base maps around this time were good enough to display appropriate information, allowing for the first thematic maps to come into being.
The primary purpose of a thematic map is to visually portray a non-visual phenomenon, usually the attributes of geographic features (e.g., the median income of a county). A good thematic map clearly shows geographic patterns that mirror patterns in the real-world phenomenon. For example, if a map reader looks at a map of income distribution, he or she should be able to quickly and intuitively identify geographic concentrations of wealth and poverty that would be the same as those seen in the field. Aesthetics is also an important goal: potential map readers are more likely to look at an attractive map and to spend enough time reading it to understand the patterns in the phenomena being represented.
Because these are in a clear conceptual order of importance to map readers (primary theme most important, reference least important), a well-designed thematic map should reflect this order in the visual hierarchy.
In addition, knowing the audience is of equal importance. Asking "Who will read the thematic map and for what purpose?" helps the cartographer decide how a map should be designed. A political scientist might prefer having information mapped within clearly delineated county boundaries (choropleth maps). A state biologist could certainly benefit from county boundaries being on a map, but nature seldom falls into such smooth, man-made delineations, in which case a dasymetric map charts the desired information underneath a transparent county boundary map for easy location referencing.
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