Cartographic design or map design is the process of crafting the appearance of a map, applying the principles of design and knowledge of how maps are used to create a map that has both aesthetic appeal and practical function. It shares this dual goal with almost all forms of design; It also shares with other design, especially graphic design, the three skill sets of artistic talent, scientific reasoning, and technology. As a discipline, it integrates design, geography, and geographic information science.
Arthur H. Robinson, considered the father of cartography as an academic research discipline in the United States, 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."
History
From ancient times to the 20th century, cartography was a craft or trade. Most map makers served several years as an apprentice, learning the skills of the master, with little room for innovation other than adapting to changing production technology. That said, there were notable exceptions, such as the occasional introduction of a novel Map projection, and the advent of thematic mapping in the 19th century highlighted by the work of Charles Dupin and Charles Joseph Minard in France. As late as 1948, Erwin Raisz's General Cartography, the standard English textbook on the subject, reads as a set of instructions on how to construct maps in keeping with tradition, with very little reflection on why it is done that way.Raisz, Erwin, General Cartography, 2nd Edition, McGraw-Hill, 1948 This was despite the fact that Raisz himself was a very creative designer, developing techniques as varied as cartograms and a style of Terrain depiction on physiographic maps that few have been able to replicate.Tyner, Judith, Elements of Cartography: Tracing Fifty Years of Academic Cartography, Cartographic Perspectives, #51 (Spring 2005), 4
Advances in cartographic production technology in the 20th century, especially the advent and widespread availability of color Offset printing, then a multitude of advances spurred on by World War II, such as Photolithography, gave cartographers a larger palette of design options, and made it easier to creatively innovate. This was synchronized with the widespread expansion of higher education, during which most cartography training transitioned from an apprenticeship to a college degree (typically using Raisz's textbook in America). The new generation of cartography professionals and professors began to reflect on why some maps seemed to be better (in beauty and function) than others, and to think of ways to improve design. Perhaps chief among them was Arthur H. Robinson, whose short but seminal work The Look of Maps (1952) set the stage for the future of cartographic design,Robinson, Arthur, The Look of Maps, University of Wisconsin, 1952 both for his early theorizing about map design, and for his honest acknowledgment of what was not yet known, soon spawning dozens of PhD dissertations. His subsequent textbook, Elements of Cartography (1953), was a marked departure from the past, with a major focus on design, claiming to "present cartography as an intellectual art and science rather than as a sterile system of drafting and drawing procedures."
Since the 1950s, a significant focus of cartography as an academic discipline has been the cartographic communication school of thought, seeking to improve design standards through increased scientific understanding of how maps are perceived and used, typically based on cognate disciplines such as psychology (especially perception, Gestalt psychology, and psychophysical experimentation), Human vision, and geography. This focus began to be challenged towards the end of the 1980s by the study of critical cartography, which drew attention to the influence of social and political forces on map design. A second major research track has been the investigation of the design opportunities offered by changing technology, especially computer graphics starting in the 1960s, geographic information systems starting in the 1970s, and the Internet starting in the 1990s. However, as much or more of the recent innovation in cartographic design has been at the hands of professional cartographers and their sharing of resources and ideas through organisations such as the International Cartographic Association and through national mapping societies such as the North American Cartographic Information Society and the British Cartographic Society.
Map types
A wide variety of different types of maps have been developed, and are available to use for different purposes. In addition to the general principles of cartographic design, some types of visualizations have their its own design needs, constraints, and best practices.
Terrain/Relief/Topography. Several methods have been developed for visualizing elevation and the shape of the Earth's surface. Some techniques date back hundreds or thousands of years and are difficult to replicate digitally, such hill profiles and hachures; others, such as shaded relief and contour lines, are much easier to produce in GIS than using manual tools. Some of these methods are designed for analytical use, such as measuring slope on contours, but most are intended to produce an intuitive visual representation of the terrain. A Choropleth map visualizes statistical data that has been aggregated into a priori districts (such as countries or counties) using area symbols based on the visual variables of color and/or pattern. Choropleth maps are by far the most popular kind of thematic maps due to the widespread availability of aggregated statistical data (such as census data, but the nature of aggregate data can result in significant misinterpretation issues, such as the Ecological fallacy and the Modifiable areal unit problem, which can be somewhat mitigated by careful design. A Dasymetric map is a hybrid type that uses additional data sources to refine the boundaries of a choropleth map (especially through excluding uninhabited areas), thereby mitigating some of the sources of misinterpretation. A Proportional symbol map visualizes statistical data of point symbols, often circles, using the visual variable of size. The underlying data may be of point features, or it may be the same aggregate data used in choropleth maps. In the latter case, the two map types are often complimentary, as variables that are inappropriate to represent in one type are well-suited for the other. A Cartogram purposefully distorts the size of areal features proportional to a chosen variable, such as total population, and thus may be thought of as a hybrid between choropleth and proportional symbol maps. Several automated and manual techniques have been developed to construct cartograms, each having advantages and disadvantages. Frequently, the resultant shapes are filled as a choropleth map representing a variable thought to relate in some way to the area variable. An Isarithmic map (or isometric or isopleth or contour) represents a continuous field by interpolating lines wherein the field variable has equal value (an isoline). The lines themselves and/or the intervening regions may be symbolized. Some choropleth maps may be thought of as rough approximations of isarithmic maps, and dasymetric maps as slightly better approximations. A Continuous tone map represents a continuous field as smoothly transitioning color (hue, value, and/or saturation), usually based on a raster grid. Some have considered this to be a special type of unclassified isarithmic map, while others consider it to be something fundamentally different.Mark P. Kumler & Richard E. Groop (1990) Continuous-Tone Mapping of Smooth Surfaces, Cartography and Geographic Information Systems, 17:4, 279-289, DOI: 10.1559/152304090783805681
A Chorochromatic map (or area-class) visualizes a discrete/nominal Field (geography) as a set of regions of homogeneous value. A Dot distribution map (or dot density) visualizes the density of an aggregate group as representative dots (each of which may represent a single individual or a constant number of individuals). The source data may be the actual point locations of the individuals, or choropleth-type aggregate district statistics. A Flow map focuses on lines of movement. A wide variety of flow maps exist, depending on whether flow volume is represented (usually using visual variables such as stroke weight or color value), and whether the route of flow is shown accurately (such as a navigation route on a Road map) or schematically (such as a Transit map or airline route map) Although these are called separate "maps," they should be thought of as single map layers, which may be combined with other thematic or feature layers in a single map composition. A bivariate map uses one or more of the methods above to represent two variables simultaneously; three or more variables produce a multivariate map.
Design process As map production and reproduction technology has advanced, the process of designing and producing maps has changed considerably. Most notably, GIS and graphics software not only makes it easier and faster to create a map, but it facilitates a non-linear editing process that is more flexible than in the days of manual cartography. There is still a general procedure that cartographers generally follow:Dent, Borden D., Jeffrey S. Torguson, Thomas W. Hodler, Cartography: Thematic Map Design, 6th Edition, McGraw-Hill, 2009, p.205Slocum, Terry A., Robert B. McMaster, Fritz C. Kessler, Hugh H. Howard, Thematic Cartography and Visualization, 3rd Edition, Pearson-Prentice Hall, 2009, p.212 Planning: The iterative nature of modern cartography makes this step somewhat less involved than before, but it is still crucial to have some form of plan. Typically, this involves answering several questions:Tyner, Judith A., Principles of Map Design, Guilford Press, 2010, p.23 What is the purpose of the map? Maps serve a wide variety of purposes; they may be descriptive (showing the accurate location of geographic features to be used in a variety of ways, like a street map), exploratory (showing the distribution of phenomena and their properties, to look for underlying patterns and processes, like many thematic maps), explanatory (educating the audience about a specific topic), or even rhetorical (trying to convince the audience to believe or do something). Who is the audience? Maps will be more useful if they cater to the intended audience.Muehrcke, Phillip, An Integrated Approach to Map Design and Production, The American Cartographer, V.9 #2 pp.109-122, doi:10.1559/152304082783948529 This audience could range from the cartographer herself (desiring to learn about a topic by mapping it), to focused individuals or groups, to the general public. Several characteristics of the audience can aid this process, if they can be determined, such as: their level of knowledge about the subject matter and the region being covered; their skill in map reading and understanding of geographic principles (e.g., do they know what 1:100,000 means?); and their needs, motivations and biases. Is a map the best solution? There are times when a map could be made, but a chart, photograph, text, or other tool may better serve the purpose. What datasets are needed? The typical map will require data to serve several roles, including information about the primary purpose, as well as supporting background information. What medium should be used? Different mapping media, such as posters, brochures, folded maps, page maps, screen displays, and web maps have advantages and disadvantages for different purposes, audiences, and usage contexts.