For this month’s Geospatial Frequently Asked Question (G-FAQ), I continue the February 2012 piece on what makes up ‘good’ map. As a quick recap, here are the core questions I will address in this two-part series:
How does intent and audience come into play when designing a ‘good’ map? How do I decide what elements to include on map? Are there any general recommendations that can be offered to create an effective map? What layers are crucial to include on a map?
In February, I discussed my first two suggestions on the topic (they are re-iterated below); and in this edition of G-FAQ, I conclude the series with my final three suggestions:
- The audience for and purpose of your map matters above all else.
- Decide on the final format and presentation of the map.
- Add the map elements that make sense for your audience.
- As with all of the recommendations I have made in this two-part series, the map elements you add should match the audience and its purpose. If the map is intended for a group of young children for educational purposes, then you will likely choose to include a different set of elements than you would for a map you intend to distribute to a group of professionals. When adding each of the map elements below, be sure to ask yourself why you are including it; if you can come up with a good answer, then the element should be included. With that in mind, I have divided the most common map elements into three broad categories:
- Elements most maps have:
- A scale bar to show distance as represented by your map. There are a wide variety of formats for a scale bar, choose the one that matches your theme the best.
- A North arrow to tell people how to orient themselves on the map. Many people choose true north for their arrow as this points directly to the top of our globe as opposed to magnetic north.
- A legend to explain the meaning of the colors and symbols used on the map.
- Elements that you should use when appropriate:
- A title that is informative to the audience about the intent or topic the map addresses.
- Labels can be an important addition to illustrate unclear points or to highlight key features of interest.
- For a map presented to an academic or research audience, you might consider adding the source of the information/data, how the information/data was processed and the projection/datum used.
- Other items to consider include a copyright symbol, the name of the map maker, the creation date and/or a project description.
- Elements that illustrate space:
- An inset can be used to zoom in on a smaller area you need to show in more detail; for instance, your map focuses on Maryland but your inset zooms in on the Baltimore metropolitan area.
- A locator map can be used to show your current location on a small but wide-area map; for instance, your map focuses on Baltimore but your locator map shows the location of this city on a small map of the East Coast of the USA.
- An index map to show the location of this tile on a large map that is broken into smaller tiled components; for instance, a small index map of the entire Baltimore metro area with the current map tile (only 1/20 of the total area) indicated on it.
- Use the space available on your map effectively.
- I tend to think that less is more when it comes to map making – this concept has a direct impact on effective use of space in your map. With any map you create, there are only so many pixels you have available to work with; so make sure your final design makes the most of this space. Here are several tips I can offer you with regards to using your map space effectively.
- Carefully consider the placement of all map elements and layers.
- When it comes to the placement of map elements, the upper left corner of your map will get the most attention while the bottom right will get the least. Make sure to arrange your map elements accordingly – for example, the map title is often quite important, hence most people choose to put them on top. While a copyright is important to a certain slice of the legal world, to most it’s rather unimportant and thus often found on the bottom of a map.
- When it comes to the placement of the points, lines, polygons etc. that are your foreground layers (see below for a definition of this term), it is generally best to place the focal point in the center of page. By focal point of your map, I mean the subject of your map; so if the theme of your map is to show the parks in downtown Boulder, CO, it would be best to place downtown Boulder at the center of your map. It is a common practice to make the most important features of your map the largest (and perhaps brightest) items displayed.
- Decide on the scale that is most effective for the topic you are trying to convey and plan your space and map elements accordingly. For example, your goal is to show the largest cities in Illinois. If your map is to be printed on a notebook-sized piece of paper, then you do not want to show the entire Midwest; rather you would only show a bit of the states that surround Illinois and with small labels for your Illinois cities. Whereas, if you planned to print the same map on a 2-foot x 18-inch poster, you might show more of the surrounding states and use larger city labels that would be visible from several feet away.
- Find a balance between white, open spaces and those spaces that are occupied by the elements, features, layers, etc. included in your map. Too much of one or the other can create a map that is either boring and uninformative (i.e. with too little info), or one that is too busy and thus uninformative as well (i.e. with too much info). Evenly spacing the items on your map can help to create a nice balance of open and colored spaces. In the two JPEGs below, I have tried to illustrate the difference between an overload map and one that makes effective use of space. The goal of this map is to show perspective home buyers the locations of Boulder’s elementary, middle and high schools (FYI – I have eliminated elements I should have included for the purpose of this illustration). The first map is completely overloaded with information that would be meaningless to illustrate this point; while the second map finds a balance between those items that are crucial to illustrating school locations and those that are not.
- As a final tip, remember that experimentation is good – if you’ve never tried it out, then it’s hard to say if it looks good or not. Move map elements, try various color schemes, test out new fonts on your friends, design some crazy new symbols – making maps should be fun! It’s not uncommon that I spend several hours over multiple days working on the final layout of a map I need to put together; it’s amazing what walking away from a map and then picking it back up a day later can reveal. What looked perfect on Monday might very well look confusing and overloaded on Tuesday.
- Decide on the map layers that matter most to your audience and display them effectively.
- When you think about layering the data on your map, there are three basic categories to consider: background, reference and foreground layers. Each layer has its own set of principles to help guide your decisions with regards to colors, labels and other visual considerations.
- A background layer(s) establishes where your map is set with regards to both the physical and cultural environment. For instance, if you are creating a map of schools in the City of Boulder, you might use city boundaries as one of your background layers. Background layers should use muted and possibly transparent colors so as to not draw extra attention to them.
- A reference layer(s) has the spatial information you need to illustrate the point of your map more clearly. In my example of a City of Boulder school map, a useful reference layer is the major streets in Boulder; including all of the minor and major streets would likely overload your map. Reference layers can use more intense colors and often include labels.
- A foreground layer(s) is the focal point of your map. In my example of a City of Boulder school map, the focal layer would be the locations of the schools within the city. Use bright colors for foreground layers and make sure you use labels, halos and other outlines to make these layers stand out.
- As a final visual tip (and a reiteration from the first part of this series), when you are choosing symbols to use on your map, make sure they are intuitive. Many industries have a set of symbols they commonly use. For instance, if you are showing the path of a river, it makes sense to show this as a thin blue line as opposed to a black line which is commonly used to show roads; or as a dashed black line which is commonly a railroad track.
After my lengthy two-part series on what constitutes a good map, I am sure most of my readers’ eyes have glossed over if they have even read this far! For those that have stuck it out, hopefully you have uncovered several interesting points on the topic. In sum, my feelings on making a ‘good’ map revolve around two central tenets: (1) your map should match both the expertise of your audience and the complexity of the topic; and (2) keep it simple as less is often more. With that in mind, I bring this two part series to a close; and until next month’s edition of G-FAQ, happy map-making!
Do you have an idea for a future G-FAQ? If so, let me know by email at firstname.lastname@example.org.
Find Out More About This Topic Here:
- Harvard University GIS Class Notes
- Penn State University Surveying Class Notes
- University of Colorado Cartography Class Notes
Brock Adam McCarty