Cartographer's Toolkit

Map Making Tips, Tricks, and Inspiration

A New Kind of Directional Icon

March 26th, 2017

Maps that use projections in which North is only constant along meridians are disingenuous when it comes to their north arrows and scale bars, since both scale and North vary depending on where they are on the map. On large scale maps this matters very little. On medium and small scale maps, however, this matters a lot. The typical solution for the directional indicator is to display graticule lines instead of a north arrow. There are some potential solutions for scale bars, too, but I will focus only on the directional indicators in this post.

The problem with using graticules is that they can clutter up the map unnecessarily. You can seek to minimize that clutter by using thin gray line symbology. In this example, you see how a thin gray graticule looks. Also notice that the north arrow that I’ve placed here solely for purposes of illustration is definitely erroneous for most parts of this map.

Graticules and north arrow

You can go a step further and run the graticule lines only over the portions of the map that aren’t as important: the oceans, for example. That isn’t always possible, especially for those of us who make extensive use of single-layer basemaps such as that shown above, where there is no way to place the graticule layer between the oceans and the land. In this particular example it wouldn’t much help to run the graticules solely over the ocean area anyway, since there is too little ocean area compared to the land area and therefore only a single meridian line would be visible.

In no way is a graticule grid covering this entire map a bad thing. But what if there might be another option to consider on maps that have a lot more information?

What if we made an icon out of the graticule grid to illustrate the directions, placed in a corner of the map just as we would have done with a north arrow if it had been an equirectangular projection? An illustration of this is probably the best way to explain it:

Map with graticule icon

Zooming in to the lower-right corner of the map:

Graticule icon zoomed in

To create this–and here I’m using ArcMap but it should be a very similar process in your GIS of choice–I created a new polygon data layer and edited it such that it contained one polygon of the extent of the map. This was pasted into a new data frame and that new data frame was set to the same projection as the first, then this data frame was zoomed to the extent of the new polygon layer. Now they both show the same exact location.

The new data frame needs to have the same height/width ratio as the main data frame so that the exact same graticules will show up in your graticule icon that would have shown up on the map itself had you placed them there. In this case the main page is 8.5 by 11 inches, so the secondary data frame is .77 by 1 inch.

The graticules, from Natural Earth data, are placed in this data frame and styled as thin gray lines, and the data frame is placed in the corner of the map along with the cardinal direction indicators in a nice serif font with matching gray font color.

As a side note, if anyone has seen this technique on any other existing maps please let me know as I have not yet come across it, and I would edit the “new” out of the title of this post accordingly.

January 6th, 2017

I’ve been using a new vector tile style editor to create some maps. The editor is called Maputnik and is still in early development, but it is usable even at this early stage. I’m really impressed with how much of the mapbox gl js spec has been implemented and the multitude of complex tasks that it makes easy.

Here’s a couple of screenshots from a style I’m working on called Camo:

screenshot1 screenshot2

Notes on a Map

November 3rd, 2016

I like to keep a Google Doc full of inspiration maps for whatever projects come up. Here’s one that’s in my inspiration doc and a few notes on techniques that are de rigueur in journalism mapping. 




Overall, this map by The Washington Post is clean and crisp. The hillshade is very subtle but not non-existent. We have an area indicated by dark gray shading and labeled straight on the map with a dark gray label. This is a good reminder that sometimes a map key isn’t needed if you can label the item(s) directly on the map.

They’re using a thin white halo around the place names in the main map (note halos are not present around “SYRIA” in the inset though I’m not sure if that was intentional). All caps are used for country names in bold black. We have bold black mixed case for major cities and regular black mixed case for minor cities. Blue italic serif font is used for the water feature labels. This constitutes a nicely executed, normal, typeface hierarchy.

The main two things that I really want to point out here, though, are the arrows and the arrow labels. The arrows indicate movement by means of gradual increases in arrow thickness, arcs, and gray drop shadows. Each arrow label matches the color of the arrow that it labels. This “pattern” of using arrows in this manner is something I’ve only recently taken note of, whether this means they are a newish development in map styling or not, I think they’re very effective.

British Library Maps, After-hour Tour

November 1st, 2016

The British Library in London is holding a contest to win an after-hours Maps and the 20th Century: Drawing the Line exhibition tour. The competition is free to enter and open until the 11th of November 2016 (midnight).

Competition Entry Form

The library sent me some additional information:

Five lucky winners and their guests will enjoy a tour with the exhibition curator and a special show and tell of rare maps from our collection, including cartographic gems like the personal maps of the kings and queens of England, the earliest maps of London and New York, and secret spy maps from the 17th century. Winners can quiz our curator on the stories behind our maps and hear how different items are selected for our exhibitions.

If I were anywhere close to this exhibit I would definitely want to enter this. Good luck to those who do!

Beyond The Core Knowledge of Cartography

October 26th, 2016


It’s difficult to teach cartography as an expert because there are fundamental concepts that one can easily forget to impart on the students, though this can be ameliorated somewhat by following a comprehensive guide to core knowledge areas such as The GIS&T Body of Knowledge*. Even so, there are certainly some concepts that nobody anticipates struggling with, teacher or student, that are unique to each project undertaken. To tackle these project-specific struggles the cartographer must possess a certain amount of patience, research prowess, and a passion for discovering new solutions through a willingness to test and revise.

It’s these project-specific issues that I haven’t written much about on this blog, instead focusing on fundamentals like typefaces, colors, and layout. Thinking about this hole in my writing, I decided to take notes while creating my most recent print map. Hopefully these notes can be instructive in not just detailing specific solutions to specific problems, but also in providing a more general picture of the types of things that come up in a typical cartography project.

These notes include ideas on skills employed, issues encountered, and paths not taken. Here is the map, in reduced resolution, because it is not considered a fully finished product just yet. The final version will be somewhere around 8-10″ on a side. The notes follow.




PROJECTION USA contiguous Albers equal area conic, an easy choice for the display of the contiguous U.S. and distances should be fairly accurate for the middle latitudes, which are inclusive of this data. This is important since I’m running some distance calculations and reporting on them in the layout, though of course I can always conduct the calculations separately from the display projection by simply starting a new GIS project with a different projection. In this case both needs are met with the one projection. So here I’m thinking, “does the projection look right? Does it calculate right (i.e., not distort the things I want to measure)?”


TRAIL DATA The trail line is a subset of linework from a university teaching database and I have not thoroughly explored its validity though comparisons by-eye to other maps of the journey show at least a superficial agreement. My need to trust this line is a problem. What if it’s wrong? How many times to cartographers blindly use data without complete knowledge of it’s correctness? In this case I’m helped by the fact that my partner in this project is a historian who can do some verification for me. In any case, verification of data should be a part of every cartographer’s workflow.


LINE RESOLUTION AND DISTANCE CALCULATIONS Another potential issue with the line trail data that crossed my mind was the issue where perhaps the line-digitizer made the line too “squiggly,” perhaps due to an unsteady hand (red line in the zoomed-in example below). If this were the case, then the distance calculations could show the Lewis & Clark crew going much greater distances than they really did. A worry, indeed, and next on my list of things to take a close look at. (Of course, conversely, distance calculations coming from a simplified line would under-report the true distance traveled.)


One section of the trail. The non-dashed black line is the real data, the dashed black line illustrates how distance would be too-low if calculated from a simplified line. The red line indicates distance would be too great if calculated from a line with inaccurate and artificially high numbers of vertices.

One section of the trail. The non-dashed black line is the real data, the dashed black line illustrates how distance would be too-low if calculated from a simplified line. The red line indicates distance would be too great if calculated from a line with inaccurate and artificially high numbers of vertices.


TERRAIN DISTANCE On a related note, the terrain distance can be much different from the straight-line distance for each segment. The straight-line distance over a ravine is shorter than the traveler’s distance, since they presumably hiked down and then back up the ravine on the other side. In the elevation profile, the true terrain distance is reported. This may account for the fact that my total mileage is greater than the total mileage reported elsewhere for this expedition.


LINE SPEED INSET: for this kind of visualization, sometimes we see the width of the line changing by speed but most often it’s depicted with a sequential color scheme instead. I’ve chosen to go with a pseduo-sequential color palette so that all the colors are clearly visible in the small space. The boldness of color needed for the size of the space is an interesting consideration that I haven’t written about before. In this inset, the expedition’s speed is calculated from a length field divided by a to/from date field converted to # of days per segment. This length field isn’t terrain-distance and thus could be a source of error. The inset still serves as a good at-a-glance comparison of the relative time it took the expedition to traverse each segment. The placement of the inset came from an inspiration map. Maintaining a rich library of inspiration maps is a must.


PAGE EFFECTS Who knew that you’d need to figure out how to create squiggly lines in Inkscape to evoke old parchment edges? Nobody, that’s one piece that can be learned on-the-fly. Also, get good at finding svg or raster textures to use as backgrounds, especially on these historic map styles. I’ve also seen lots of textures on contemporary map styles, usually in grided dot patterns. (Hint for the squiggly line page border: draw a rectangle and then use Filter>Filter Texture>Rough and Glossy and fine-tune the result with the Filter Editor as the Inkscape filters often default to startingly bold results.)


PROFILE GRAPH Exporting a profile graph is possible using a QGIS plugin called the Profile Tool. You can also create profile graphs with ArcMap’s Elevation Profile Add In. The tables of profile data that are produced for each segment of a given line can be exported to spreadsheet software to produce a nice looking graph (the graphs that are automatically output from these aren’t really suitable for a well designed map layout.) Using spreadsheet software (in my case, Excel) I made a graph, switched the progression to East–>West since that’s the direction they were headed, and further styled the graph in Inkscape. This was a process that probably took half a day or more from researching tools to implementation to styling. I even used a pen tool set to smoothing 25% to trace over the excel-derived profile line in order to create a more pleasing line (since my original profile had a point for every mile along the 4,000 mile route and created quite a jagged looking profile line.) Switching a profile graph’s direction to suit the data was a mental hurdle, overcome only by thinking, thinking, and more thinking about the data and the story I was trying to tell. This is something we’re always talking about: know your data, think about your story.


TYPEFACES The typefaces are chosen to complement the historic look of the map. Gabriola is used since there’s limited text and its decorative nature seems to suit the overall style. There are Myriad other fonts I probably could have used, and likely a better one will crop up as I revise. (The Myriad reference, ahem ahem, is a little type joke for the type nerds.)


X AXIS LABELS The x axis labels are problematic and will need to be redone. They depict distances at the segment end points, which is useful, but too jarring in the context of an x axis, which traditionally shows a smooth progression of numbers. An experiment gone awry. Sometimes, oftentimes, our experiments don’t work out. Note the axis lines and labels are in a medium-dark gray. I want them to remain firmly in the background as supporting information.


PROFILE LINE COLOR I considered changing the color of the profile line depending on the altitude. Green at low altitudes, progressing to brown, and finally white at the highest altitudes. A hypsometric tint for a profile chart! This seemed a bit much though, given the complexity of the rest of the page.


COLORS AND PRINTING The saturation of the hillshade will likely need to be adjusted once I see this printed on the final medium. It looks good on my screen but vast experience with this shows me that it can likely look too dark or too light depending on the press and the paper. Web designers have it easier in this respect. They’ll go on about how every monitor is different and that phones produce glare outside. But that’s nothing to needing a perfect print out on one media type and getting it wrong. There’s no excuses when it comes to printing a map in a known format (in this case, the map will be in a book so I will need to do a lot of exacting color proofing when the proofs come in.)


COASTLINE The overly stylistic coastline with drop-shadow was chosen specifically to comport with the historic style, though you’ll notice I didn’t interpret “historic” so literally so as to include such unfounded ornamentation as author cartouches or sea dragons. One must have boundaries. (Joke: boundaries, coastline, ahem.)


LET GO OF YOUR STYLING DARLINGS I am so hung-up on water=bright blue that when I began the map I of course made the water a very bold solid blue. It took several days of mulling over before I realized that was all wrong for this map. Pouring over the file of inspiration maps that I’ve been keeping for this project, it took only a few minutes to come up with an alternative to the blue, but only once I knew what I was looking for. This seems to be a frequent problem for cartographers who have a wide repertoire of map styles. They can intermingle to the great detriment of the final map unless time is taken to think things over. Knee-jerk styling such as my dark blue ocean (a modern map color for oceans) is only helpful if you keep to the same style-genre (e.g., historic, modern) all the time.


This wraps up my notes on the making of this map. Hopefully there will be a few bits you can use in your next project.


*The GIS&T Body of Knowledge is a great reference document when interviewing for a new GIS position. Use it as a check-list, checking off areas you have a firm understanding of and noting what subjects you need to study more.



Cartographer's Toolkit

Map Making Tips, Tricks, and Inspiration