What makes a great map?
Maps have long been invaluable tools, guiding explorers, aiding strategists, and helping everyday people navigate their world. A well-crafted map can convey complex data at a glance, illustrating geographical relationships and highlighting trends that might go unnoticed by most. Regardless of the map type or target audience, a map's goal is to effectively present and communicate information so viewers can understand and take action.
The impact of a good map versus a bad one can be profound. Accurate maps facilitate better decision-making and efficient resource allocation, which is crucial in scenarios like disaster response. Conversely, poorly designed maps can lead to misunderstandings and potentially dangerous mistakes.
Types of Maps:
There are two main categories of maps: general reference and thematic. However, there are many subcategories such as topographic, cadastral, and navigational charts. While the subcategories have overlapping traits with both the main categories and other subcategories, knowing what type of map you're making will help shape your design choices and ensure that all needed information is presented properly.
General reference maps, also known as planimetric maps, are typically the easiest to read and interpret. With no geographical knowledge required, they depict important natural and man-made features and are created to summarize the urban landscape to aid in navigation. These maps are commonly used in tourism, city maps, and Atlases.
General Reference Map of the U.S. Credit: USGS
Next, thematic maps portray collected qualitative or quantitative information related to a specific topic, such as population density or political alignments. They can represent statistical, physical, or measured data and may require specialist knowledge or an extensive legend to interpret. They don't typically include features like roads or cities (unless that is the map's focus) but instead emphasize spatial patterns across regions.
A popular type of thematic map is a choropleth map, which represents scaled data within set geographic boundaries and assigns each portion of the data scale with a color. Dot density, heat, and isopleth maps are other common forms of thematic maps. For more information on thematic maps and its subcategories, check out Nova’s Mapping 101 .
A thematic map representing vehicle miles travelled per capita in 2008. Credit: Susie Day
Like general reference maps, topographic maps summarize the landscape but include elevation data in the form of contour lines. Contour lines indicate the region's elevation or height relative to sea level, often denoted in black or brown lines. Contour lines are used only to map land elevation measurements, while bathymetric contour lines chart ocean floor depth. These maps are created using strict guidelines and are usually created by government agencies for civilian and national defense purposes.
Topographic Map of Virginia City.
Credit: USGS & the University of Nevada
Cadastral plans are visual representations of the geographical boundaries of one individual plot of land, while cadastral maps are amalgamations of many plans. These maps are usually created by a licensed surveyor and managed by municipal agencies. Government agencies can use cadastral maps for land use planning and taxation purposes.
Cadastral Map with an individual cadastral plan circled. Credit: ICSM
Navigational charts help users navigate a region's bodies of water or airfields. Nautical charts depict a significant amount of detail about the water rather than the land, which is why there is a distinction between maps (land-based) and charts (water- or air-based). Combining features from thematic, general reference, and topographical maps, marine navigational charts provide details about a region's coastlines, ocean floor, and any other hazards sailors should know about. Aerial charts indicate heights above land masses and man-made structures so pilots can be aware of hazards like cell towers during takeoff and landing.
Nautical Navigational Chart. Credit: ImproveSailing
Map Non-Negotiables:
Certain elements make or break a map. Besides the core data, the marginalia (the information outside of the core data), such as titles, labels, and metadata, improve the understandability of a map immensely. A comprehensive title allows users to understand exactly what your map is trying to demonstrate. Labels help viewers locate points of interest and give context to the map. These elements are instrumental to getting your point across so map users can analyze and leverage the map.
A map's metadata is crucial to creating a relevant, trustworthy, and citable map. Information on the data source, datum, and projection method lets users reference and replicate your work, adding to its credibility. Many projection methods are used to transform data, each modifying how it appears. Indicating whether the map was projected using a cylindrical, spherical, or another projection method can help explain visual distortions to users. Further, providing a date of creation or data collection will help viewers determine the work's relevancy, timeliness, and if it satisfies their needs.
Secondary elements like a distance scale, insets, grid lines, origin, and legend can enhance a map. Distance scales must be featured on maps with meaningful spatial relationships, such as topographical and general reference maps. Maps demonstrating regional trends or collected data, such as choropleth maps, don't need to prominently feature a scale because its presence does not impact the understandability of the map.
Map insets are extremely helpful in helping viewers understand where a particular region is situated on a macro level but can be excluded from maps focusing on large areas like continents and big countries. Grid lines create fixed points for data to be laid upon so that the output is geographically accurate in accordance with the datum used. They are featured prominently in topographical maps but can be excluded from general reference or thematic maps. An origin refers to the cardinal direction the map is orientated by, such as true north, and is typically depicted by an arrow pointing in the direction. Finally, a legend tells users how to interpret any symbols or design elements used in the map– extremely important if the symbology used is not recognized everywhere and requires explanation.
Adding these elements means the difference between viewers understanding your map and being left wondering what they’re even looking at. Nova’s PDF Map feature allows creators to toggle these elements on and off as needed.
Map Elements. Credit: Manuel Gimond
Map Design: Tips and Tricks
Once you have all your map elements, it's time to put them together. Cartography, or map-making, is one part art and another part science. How you display data will impact how users interpret your map.
Visual Hierarchy
People read maps like text, left to right and top to bottom. Consider the map's objective and intended audience when considering what your map will look like. Identify the most pressing information (this typically will answer or relate to the map's title) and place it in the forefront of the map. Any irrelevant or contextualizing information should be in the background so as not to overwhelm the map's observer and allow the most critical information to be absorbed first. The type of map you're producing will influence the laying of information with reference maps and navigational charts having a subtler hierarchy compared to thematic maps, where the theme is more important than the base layer.
Color and Contrast
When used correctly, colors can be a differentiator between two distinct things. However, too many colors can lead to confusion, overstimulation, and a lack of understanding when misused. First, the colors chosen should reflect their purpose. For example, for general reference maps, all bodies of water should be the same color rather than various shades of blue (unless your map differentiates between oceans, lakes, and rivers). A common error in selecting colors occurs when creating choropleth maps. Map makers sometimes choose clashing or inconsistent colors to indicate different themes rather than employing a color scheme to demonstrate the data's scale. Further, using too many colors overwhelms viewers and is usually caused by a messy and non-uniform data scale. People enjoy patterns they can follow, something intuitive and not likely to give them a headache trying to decipher.
Contrast is another factor to consider when selecting a color palette. Maps that lack visual contrast often have a poor visual hierarchy, meaning that all the information blends into each other, causing confusion. Against a lighter background, dark and opaque colors are best for the most important information as it brings it to the front (and vice versa for darker backgrounds). In addition to identifying essential features, contrast creates boundaries between items and increases the legibility of your map.
Symbology
Symbols represent map features like trails or lighthouses, and they come in three forms: points, lines, and polygons. Points, indicated by geometric shapes or icons like trees or crosses, represent specific places or landmarks. Lines represent features that are continuous, like rivers and roads. Polygons, filled with colors or patterns like hatching, represent vast areas such as forests or oceans. When selecting the right symbolization for your maps’ features, remember that the map size dictates how many symbols you have and of what size, with geometric shapes being easier to place in large quantities than icons like cars or waves. Additionally, if you use icons to depict features on your map, ensure that your target audience will recognize your chosen symbol or that you feature it in your legend.
Legibility: Fonts, Sizes, and Spacing
While colors, contrast, and layout are crucial, the ultimate test of a map's effectiveness is its readability. Legibility is not just about spelling; it's about font, letter spacing, sizing, and placement. These elements can transform a cluttered mess into a clear, well-crafted map.
When selecting fonts, select one or two fonts that complement each other and are readable! Once you have chosen a font, you should stick to a single stylistic variation (light, bold, regular) and only use modifications, like italics or underlines, to indicate importance. Keep your target audience in mind when selecting fonts.
For example, young children will have difficulty reading tight cursive, while older adults might have issues reading small fonts with low-differentiability. However, if your maps are creative in nature, such as fictional world maps, font experimentation may help tie your map's aesthetics together and make your map more appealing.
If you've ever opened up a book and immediately put it back down because the text was too small and squished, then you know the importance of letter spacing and sizing. With proper formatting, map viewers will find it easier to read and understand. Intuitively, the title should be the most prominent text on the map, followed by the legend and then the labels. Any optional marginalia, such as data sourcing and authorship, should be smaller than the labels without compromising legibility.
Crowded and text-heavy map of the United States. Credit: AntiqueDigitalPrint
For readability and respecting the premise of visual hierarchy, we recommend limiting your font sizes to three (four if there are footnotes or additional annotations).
Letter spacing and leading (the vertical space between lines of text) are also very important. Larger maps provide leniency as the font size can ease some spacing issues, but inconsistent or inadequate spacing leads to problems on smaller maps. Cartographers usually increase letter spacing when labeling natural phenomena that benefit from increased letter spacing, such as oceans –which are vast– and rivers, which curve, and wind. However, please be mindful not to stretch wording too much. If you have a long river or road that requires labeling throughout the map, repeat the name rather than stretching it to cover the entire feature. While loose leading can be beneficial on larger-scale maps and in labels indicating a large area like a national park, tight leading is best for maps with smaller areas.
Placement and Effects
Labels are essential to understanding a map; however, when misplaced, they can cause more issues than they solve. To avoid your labels doing your map a disservice, here are some considerations.
First, when mapping a coastline, all land features, such as seaside towns, should be labeled entirely on land, while coastline features, such as marinas, should be labeled on water. The placement helps delineate what features are water-based and which are land-based.
Next, remain consistent with positioning. Choose where the labels are positioned and keep it the same. Positioning is essential in a densely populated map showing multiple cities, countries, or landmarks. If your text does not fit within its given region and you'd have to deviate from established sizing, spacing, or positioning to make it fit, try using callout or leader lines to indicate where a label is specifying. We recommend that you sparingly use callout and leader lines to ensure they never cross over another line or label to keep your map clean and understandable.
Your labels should not fade into the background, overlap with each other, or disturb boundaries. Contrast is essential even for labels and can be achieved through halos or drop shadows. Halos highlight the label by placing a light color behind the dark text for contrast, while a drop shadow places a darker color behind the light-colored text.
Accessibility Considerations
There are an estimated 300 million color blind people worldwide and another 285 million who suffer from blindness or visual impairments. Maps rely on visuals to be interpreted but there are strategies to mitigate and even eliminate barriers for those who have difficulty seeing, and by not taking them into consideration, you'll miss a large demographic of potential viewers.
Tactile Mapping
For those who are blind or have a severe visual impairment, the inclusive nature of tactile mapping can be a great way to ensure they don’t miss out on your map. Tactile mapping uses raised lettering and braille to communicate. Those with difficulty reading standard text can feel enlarged Roman or Braille letters and understand the map through their sense of touch.
Color Blind Considerations
When mapping for those with color blindness, accommodating them is a matter of color choice. There are several types of color blindness: Deuteranopia (inability to see green), Protanopia (inability to see red), Tritanopia (inability to see blue), and Monochromacy (a complete inability to see colors). Color blind people will have difficulty differentiating between colors that are too similar or belong to the color family they can’t see at all. To prevent confusion, pair a color-blind-friendly palette (see below) with clear borders and try incorporating patterns to ensure your distinctions are clear.
A color-blind-friendly palette. Credit: GISPlanning.
Dyslexia Friendly Fonts
While maps are primarily visual aids, they still require a fair bit of reading to interpret as intended. For those with dyslexia, reading can be a significant challenge. You can make a significant difference by selecting a dyslexia-friendly font for your map. When choosing a font, consider a sans-serif typeface like Arial or Verdana. These fonts appear less crowded, making it easier for those with dyslexia to differentiate between letters and thus feel more accommodated in your map design.
Cartography is a complex practice that involves striking a balance between information and understandability. Without maps, stories have no context, and neither does geographical data. Creating crisp, clean, and accurate maps that are inclusive and accessible is the key to effectively relaying various information from geographical themes and trends to relevant navigational aids. Ultimately, it's one thing to collect data and create a map; it's another to make a great map–one that users can leverage and take information from. Hopefully, with the considerations described above, you'll be one step closer to creating a great map.
Want to test your map-making skills? Head to Nova, play around with the new map layers & details (like labels and contour lines), and create your own exportable PDF maps!
Best,
Cece and the Nova Team