Cartographic design

Cartographic design is the process of creating a map to represent geographic information. Effective cartographic design employs general principles and techniques common to any form of design, along with theory and techniques specific to cartography. They combine to create a map that is visually attractive, while efficiently communicating desired information to an intended audience. Cartographic design is a craft that applies artistic and scientific principles to create products that are both beautiful and functional.

Arthur H. Robinson, an American cartographer influential in thematic cartography, stated that a map not properly designed "will be a cartographic failure." He also claimed, when considering all aspects of cartography, that "map design is perhaps the most complex." Robinson understood that a map must be designed with consideration to the audience and its needs.

Designing a "Good" Map
As with other forms of design, cartography is often subjective, with much room for the style and taste of the cartographer. If what makes a "good" or "bad" map is open for debate; how can one tell the difference? A way to evaluate whether or not a map is either "good" or "bad" is to follow certain design rules.

One possibility is to acknowledge that almost all maps need to be useful, and serve a particular purpose for a particular audience; thus, one may consider the utility of a map to evaluate its quality. With respect to utility, there are at least 6 definable elements that separate a good map from a bad map:
 * clarity: the map focuses on its purpose with as little distraction as possible.
 * order: the elements of the map are organized to guide the map reader to accomplish the intended purpose.
 * balance: elements are distributed to give the map a feeling of "evenness."
 * contrast: important elements stand out clearly against less important ones.
 * unity: the various elements come together to make the map appear as a single coherent whole.
 * harmony: the elements all seem to fit together naturally.

Good map design achieves other goals as well. For example, Alan MacEachren explains that a well-designed map "is convincing because it implies authenticity" (1994, pp. 9). An interesting map will engage a reader. An abundance of data or a map with several variables allows comparison and analysis. These factors add to the meaningfulness of the map and often stimulate ideas which could lead to further research.

While maps are usually judged on their functionality, they also have an aesthetic quality, and there is value in a map that is aesthetically pleasing. In a purely practical sense, potential users are more likely to look at an attractive map and spend the time necessary for the map to achieve its purpose.

Map Purpose
The purpose of a map is what the cartographer intends, but whether or not the user of the map understands that purpose depends on the design. From the very beginning of mapmaking, maps "have been made for some particular purpose or set of purposes". Some maps may have a very specific message to convey, some may focus on one narrow topic, while others may portray many themes and be useful for a wide variety of tasks, but almost every map has some purpose (whether general or specific) behind its design.

Maps can be categorized into a few types of purpose:


 * Descriptive maps tend to have a broad purpose, showing the features on the landscape as accurately as possible, allowing the map reader to use that information for a variety of tasks.
 * Narrative maps have a specific message to convey.
 * Rhetorical or Prescriptive maps attempt to convince map readers to have a particular opinion or take a suggested action
 * Exploratory maps typically do not have a particular message because the cartographer is using the map to explore the geographic data and discover patterns in the world.

Audience-focused Design
Because most maps are intended to be used for some purpose, it is the task of the cartographer to create a product that the intended audience can use easily and correctly. The better the cartographer understands the reader, the better he or she can fine tune the map. This audience can vary widely, from the person making the map for them self (especially when the map is being used as a part of the research or decision-making process), to a small group such as a single department, to the entire world. There are several characteristics of the users of a map that need to be considered:


 * Subject Knowledge: how much do they know about the topic being covered by the map? The less they know DrymarchonRange Ec copyPNG.png(or more specifically, the less the cartographer can safely assume that they know), the more the map will need to explain.
 * Regional Knowledge: how much do they know about the region being covered by the map? Readers who know the area will more quickly grasp the message and its significance. The map may need to include more elements to help unfamiliar readers make sense of the geographical context of the topic, such as inset maps, reference layers, and labeling.
 * Geospatial Knowledge: how much do they know about the terms, concepts, and techniques of Geography and Cartography? Much of the construction of a map makes assumptions about the ability of readers to decipher the symbols and relate them to the real world. Concepts such as  scale factor,  projections, and standardized  symbology may confuse some readers.
 * Usage Context: maps come in a variety of media and environments: large wall maps, slides in presentations, atlases, GIS displays, mobile phones, and many more. Each of these environments has its own opportunities and constraints for design. Effectively designing maps to be used in multiple environments can be especially challenging.
 * Motivations and Bias: each map reader approaches the map with a wealth of experience and expectations that will influence what he or she gets from the map. A map intended to convince an audience that is already skeptical about or opposed to the message will need to be designed differently than a map that "preaches to the choir."

An example of audience-focused design can be seen in the map entitled "Distribution of the Genus Drymarchon." The purpose of the map is to show the current extent of the snake genus Drymarchon. The author takes a number of liberties on this map due to his knowledge of the audience base. First, the author does not explain what Drymarchon is because he assumes that the audience already knows what a Drymarchon is. Second, there are no place labels because the author knows that the intended audience of the map only wants to know the general extent of the snake genus throughout the Americas and would not care about place labels. Third, the author uses political boundaries to show the extent of Drymarchon (an unusually simple approach for showing range-limits), because he knows that would be sufficient for the intended audience and the context in which the map would be viewed.

Composition
A map typically consists of multiple layers or themes that convey the purpose of the map. Composition is the technique of designing the different objects and layers in the map to be aesthetically attractive and useful, and to work together effectively as a whole (gestalt). A map that is well-composed is clear and easy to use, while poor composition results in maps that appear confusing and complicated.

Layout
Map Layout or Map Composition is the design and arrangement of a map image and supporting elements to effectively convey information to map users. These elements commonly include:
 * title
 * One or more map images, including inset maps
 * legend or key
 * Visual or narrative explanation of the map scale
 * Supporting media, such as photographs, diagrams, and text
 * North arrow or other depiction of orientation
 * Metadata, explaining such information as the currency of the information, sources used, projection, copyrights, and authorship

The effective design of these elements makes the map easier to understand and use as well as making it more aesthetically pleasing. Cartographers have adopted many of the principles developed in the field of graphic design, such as visual hierarchy, visual balance, and the effective use of typography.

Aesthetics
Aesthetics deals with beauty or artistic appeal. . In cartography, the aesthetic aspects of a work influence the overall quality of that work. It is important for cartographic works to have aesthetic features because the aesthetic appeal has a significant impact on the quality and user-friendliness of that work. When choosing between two similar maps, one usually chooses the map that has more aesthetic appeal. As cartographer Felix Ortag said, “A beautiful map is not necessarily a good map, but a good map should be beautiful.”

Aesthetics in cartography can take one of two forms:


 * 1) Responses to the map itself as an aesthetic object. This can be accomplished through details the cartographer chooses to put emphasis on, the color or combination of colors included in the map, or artistic form the map takes (i.e., "this is a beautiful map").
 * 2) The subject of the map symbolized. An example of this would be the cartographer creating an expression of terrain which forms an imagined visual experience and elicits an emotional response to the real-world landscape being depicted (i.e., "this map shows how beautiful this place is").

Map symbology
The quality of a map’s design affects its reader’s ability to extract information and to learn from the map. Cartographic symbology has been developed in an effort to portray the world accurately and effectively convey information to the map reader.

Color
Color can be a powerful tool when designing a map to convey information. It can help show increasing or decreasing values, differentiate types of features, establish a visual hierarchy among map layers, or prescribe action, among many other uses. It is also crucial in building the aesthetic appeal of a map. How the cartographer displays the data in different hues can greatly affect the understanding or feel of the map.

Because color can be utilized by computers so easily, it is often misused. Mark Monmonier famously stated, "Color is a cartographic quagmire." It is crucial for cartographers to understand the theory and application of color in maps.

Map Labeling
Text is a crucial part of any quality map. Text simultaneously serves several purposes:


 * It identifies unique features (e.g., "The United Kingdom")
 * It places features within broader categories (e.g., "park")
 * It locates features within a general geographic context (e.g., this vegetation stand is within "Zion National Park")
 * It explains the characteristics and meaning of features on the map (e.g., "high economic potential zone")
 * It prescribes and proscribes action (e.g., "camping not permitted here")
 * It can add to the aesthetic beauty of a map
 * It can give a map an aesthetic feel (e.g., using a typeface that looks modern or historical)

The effective use of type can further all of these goals, while the poor use of type can produce maps that are confusing and unattractive.

Type
Typography is the art of working with, processing, and designing type. A lot of work goes into designing fonts, style, and making unique typefaces. In cartographic design type often plays a large role in getting an idea across. Components of type include weight, size, spacing, and many other aspects. http://wiki.gis.com/wiki/index.php/Font http://wiki.gis.com/wiki/index.php/Typefaces

Map generalization
A good map has to provide a compromise between portraying the items of interest (or themes) in the right place for the map scale used, against the need to annotate that item with text or a symbol, which takes up space on the map medium and very likely will cause some other item of interest to be displaced. The cartographer is thus constantly making judgments about what to include, what to leave out and what to show in a slightly incorrect place - because of the demands of the annotation. This issue assumes more importance as the scale of the map gets smaller (i.e. the map shows a larger area), because relatively, the annotation on the map takes up more space on the ground. A good example from the late 1980's was the Ordnance Survey's first digital maps, where the absolute positions of major roads shown at scales of 1:1250 and 1:2500 were sometimes a scale distance of hundreds of meters away from ground truth, when shown on digital maps at scales of 1:250000 and 1:625000, because of the overriding need to annotate the features.

Terrain


Terrain or relief, the three-dimensional shape of the Earth's surface, can be represented on maps using a variety of methods, each with different benefits and drawbacks. One of the most common methods is using Contour lines to show locations of equal elevation. Other methods include Shaded Relief, Hypsometric Tinting, and Tanaka contours.

The process of creating terrain layers in maps has become much easier with the creation of Digital Elevation Models (DEM) and Triangulated irregular networks (TIN). These data sets (raster and vector respectively) can be used to create the methods of terrain representation mentioned above in a GIS.