The Colors of Mars

I can’t quite remember why I started, but for the past several weeks I’ve been thinking on and off about hypsometric tinting schemes for the planet Mars.

There are a wide variety of elevation coloring schemes that exist for the Earth; I won’t get into details here, but most of them start with some sort of green in the low areas and move through some combination of brown/yellow/orange/red until they reach white in high areas. It’s a visual proxy for land cover, though it’s a rather flawed one.


Typical Earth hypsometric tints, from the Patterson & Jenny Cartographic Perspectives article linked above.

But what we use for the Earth doesn’t entirely make sense on Mars: its mountains are not snowy, nor are its valleys green (of course, we often tint desert valleys green on Earth maps). Setting aside the idea of these colors mimicking land cover, Mars is a vastly different place, and so it feels wrong to me if it doesn’t look different than Earth.


Unfortunately, the great majority of Mars maps (that I have seen) use a rainbow scheme for their hypsometric tints, which make a mess of everything (though they do certainly look different). They are garish and confusing, and also problematic for any readers who have color vision impairments.


A rainbow of colors on Mars, by NASA/JPL/USGS

Some Alternatives

Fortunately, there are a (very) few maps out there that take a non-rainbow approach.


Let’s meet our contestants!

Kenneth Field’s (Is There) Life on Mars? starts with deep purple in the basin of the Hellas Planitia, and then proceeds through some nice rusty oranges before settling on a sandy tan (though the its context on the map makes it look more yellow).


Kenneth Field

Henrik Hargitai’s Mars map for Country Movers takes an unusual approach, in that it is at its brightest in the low areas, starting with yellow and turning deep red as elevation increases, and finally finishing off with a little dark pink highlight on the tops of Olympus Mons and the Tharsis Montes.


Henrik Hargitai

My own scheme, which I’ve never actually used except for in this very blog post, is inspired by the colors on the surface of Mars. Due to atmospheric effects, the Red Planet is actually mostly red only if you’re looking at it from space. It’s more brown & tan on the surface, at least if the photos from Curiosity are any indication. I did make the low areas a little reddish just to contrast with the yellow highlands.


Daniel Huffman

Finally, Daniel Macháček’s Topographic Map of Mars takes things in another direction; avoiding the Red Planet stereotype, he opts for blue (and a bit of purple) in the lowlands, moving through grey into a cool brown for the higher elevations.


Daniel Macháček

Honorable mention goes to Eleanor Lutz’s Here There Be Robots. It’s a medieval-inspired map, and it uses a a tint scheme that looks to be based on an Earth hypsometric tint scheme. On that account, I didn’t include it above (though it’s a lovely work and you really should check it out).

Other Observations

  • All of these schemes do a good job of highlighting the Martian dichotomy — basically, the northern hemisphere is a few kilometers lower than the southern hemisphere.
  • One good thing about a typical Earth hypsometric scheme is that it includes a wide range of colors (greens, yellows, oranges, greys, etc.), which means it can show more detail. The schemes above all cover a narrower color range. But, if you’re going for a color scheme inspired by the actual look of Mars, which 3 of the 4 of them are, you’re kind of limited. Mars is much more uniform in color than the Earth.
  • Much of the Mars elevation range is taken up by four giant mountains. Notice in Ken Field’s scheme how little of the map area is tan, and yet that tan covers half of the elevation range of the scheme. Likewise, Hargitai uses a deep red to cover a pretty large chunk of the elevation range.

These are the only non-rainbow Mars schemes I’ve found. You might know of some others, but in any case I was a little surprised at A) how rare they were, and B) the degree of variation among them. By collecting them in one place, perhaps I’ve given any future Mars mappers some inspiration for their efforts.

A Cartographer’s Story

In the years since I wrote On Salvation, I have received a number of comments about how it’s resonated with other people in the field (and without). I’ve long felt we, as a community, need to hear more stories like this. In any creative field, including cartography, there’s a lot of emotional investment in the work, and learning about that is just as important as learning technical skills.

So, John Nelson and I are launching a new project: A Cartographer’s Story. Drop by and read stories from your fellow mapmakers about the personal & emotional relationships they have with their work. And please share yours: we could all befit from hearing about your own journeys.

An excerpt from the website:

Every act of creation is personal. Behind the cartographic theory, tools, and techniques, there is a human being who struggles, who triumphs, and who is driven by more than just a need to earn an income.

While our community has a rich culture of sharing project walkthroughs and clever tricks, our colleagues also need to hear about the personal and emotional relationships we have with our maps. We invest ourselves in creating works that are meant to stir the hearts and imaginations of others—and in return our works invest in us. What are your stories? How has mapping moved you or changed you? Did it encourage you through a tough time? Teach you something about yourself? Represent a significant relationship in your life?

None of us is alone in finding empowerment, redemption, or salvation in our work; this is the gift of working in a creative field. Please consider sharing that gift by telling us stories about the power your maps have had within your own life.

We’ll see you there.

Financial Transparency

As a freelancer, I often wonder how I am doing financially as compared to my colleagues. Not out of a sense of competition, but just to answer the persistent question: is this normal? Am I earning a “typical” living? Do I get an unusually small or large amount of money from selling prints? Things like that, born of curiosity. I can look at the great work of a colleague and think it’s valuable, but the big question is: does the rest of the world value their skills the way that I do?

I find the financial opacity of the freelance world a bit intimidating, and I suspect that some others do, too—particularly those who are interested in freelancing, but haven’t yet jumped in. So I’d like to do my part to lend transparency by laying out my financial picture for all of you. Maybe it’ll be valuable for someone, and if so, I’d be interested to hear about that in the comments.

Freelance Earnings

I have been freelancing since I took my Master’s degree from UW–Madison in May 2010. I pretty much exclusively make static maps. Perhaps someday I will become interested in making interactive maps, but for now I’ve focused on an ArcMap/QGIS and Illustrator/Photoshop workflow.

I had only a scant few projects before 2012, and in any case my pre-2012 records are a bit disorganized, so let’s start after that. My earnings from freelance cartography have been:

2012: $12,016.34
2013: $20,352.75
2014: $8,508.58
2015: $10,881.25
2016: $22,795.00

I have also earned money from some other non-mapping freelance work. I do editing and layout for Cartographic Perspectives, and I’ve done some bits of paid writing, other design work, etc. This income isn’t terribly relevant to those who are wondering about the mapmaking business, but I’ll include it here for the sake of completeness:

2012: $1,128.08
2013: $1,528.00
2014: $7,014.00
2015: $10,194.00
2016: $2,000.00

These bits of side work, as well as my teaching (below), have been very helpful in leaner years.


I teach from time to time at UW–Madison, covering the Introductory Cartography course. Again, not too relevant to the subject of freelance earnings, but perhaps interesting if you’re curious about what adjunct teaching pays. My take-home pay for one semester of a 40% appointment is $6,954. This number seems to compare favorably with what I’ve seen posted at other institutions, or heard from colleagues elsewhere.

Sales of Prints

Finally, the last piece of the puzzle is sales of prints. Instead of making maps for clients, I sometimes (or often) spend time making maps for no one in particular. And then I’ll put them up on Zazzle in case anyone wants to buy them. I’ve also occasionally printed maps locally and sold them through an art store or by word of mouth. But Zazzle is where almost all of my sales happen.

My earnings from sales of prints:

2012: $772.39
2013: $678.68
2014: $270.19
2015: $116.52
2016: $797.54

I don’t usually do any sort of marketing other than a tweet or two, plus a link on the blog leading to the Zazzle item, so those figures could potentially be higher if I tried harder.

And, if you’re curious as to what sells and what doesn’t, here’s a breakdown of Zazzle sales:

Again, if I tried to market these, I might be able to push a few more. Getting them into local stores can be tough because printing costs are pretty high unless you want to order them in quantities of hundreds, and thus stores either have to accept a tiny margin or offer the posters at comparatively high prices.

Fame and exposure are generally free, and often much more plentiful than actual payment. It takes a lot of clicks before someone actually buys—I have also seen this behind the scenes with the Atlas of Design. I often see colleagues whose work gets a lot of attention, and who are offering cool prints, and wonder if they are receiving lots of praise with little money behind it.

Concluding Thoughts

I never really intended to be a freelancer, because I dislike instability, and the numbers above fluctuate wildly. But I fell into it accidentally anyway, and it’s been great, but it’s definitely not a life I would have been able to choose if I had to worry, for example, about dependents. I’ve also had the advantage of a safety net, in that my partner Kate earns much more than I do and, in the early years, carried well more than her fair share of our joint expenses.

I also haven’t been able to save for retirement very much these last few years, as I’ve been focused on more day-to-day expenses. Fortunately, a sizable recent contract has given me an extra boost that will soon let me finally put some money away.

I hope all this stuff above offers some useful insight as to one freelancer’s life. I’m sure some others earn more, and some others earn less. I’d encourage others who are comfortable doing so to share their own financial information, to make the picture a little broader.

An Arrangement of Islands

As per my usual modus operandi, here’s two versions of a little something I made for no other reason than love:

Classic Overview.png

“Classic” version — click to view a PDF


“Hip” version — click to view a PDF

It’s a very large poster — 24″ × 36″, in fact. So, I recommend clicking those images to browse around the PDF versions. Or just look at this quick pair of detail images, instead:

Details of the two styles

Details of the two styles

Notes on the Design

  • A few people have asked me if this poster shows all of the islands in the Great Lakes. The answer is no. There are roughly 35,000 others which I did not have space to include. I have shown the largest.
  • They’re not quite in order of size. I did a little shuffling within rows, to help things look a little more visually even.
  • There’s some room to quibble over what is an island in the Great Lakes. Wolfe Island is at the mouth of the St. Lawrence River as it enters Lake Ontario. Walpole Island is formed by the delta of the Saint Clair River, and in any case isn’t on one of the five Great Lakes proper. I erred on the side of inclusion.
  • Despite that inclusive stance, I did not include Copper Island, which owes its island-ness to a canal.
  • I love the three stages of waterline perception on the Classic version. From far enough away, it looks like a simple stroke around the islands. As you get closer, it looks like a shadow, instead. And closer still, you can see the parallel waterlines.
  • I started out with a very minimal design concept in my mind, then quickly started loading it up with unnecessary stuff. “Hey, what if I add towns, roads, parks, rivers, etc.?” Then I slowly, and thankfully, started dropping each of these elements, sometimes because it seemed like a big hassle, and sometimes because colleagues urged me to keep it simple and clean. Which was the entire point, as I had forgotten.
  • Lake Erie does have islands, but the largest, Pelee, was just a bit too small to make the cut. Perhaps I’ll someday do a “Part 2” poster, featuring the next group of islands in the size sequence.
  • I used Adobe Caslon for the Classy version because I knew it had great swashes.
  • I used Mostra Nuova for the Urban version because I paid too much for those fonts to not use them in every single project.
  • I used CanVec 250k data for Canada, and for the US I used TIGER/Line data that I simplified to match the Canada data.
  • Fun/annoying fact: I could not easily obtain land polygons, so I used waterbody polygons instead, then inverted everything to get land shapes.

As per usual, I’m putting these up on Zazzle, in case you are in the extremely small group of people who want to pay money for something like this (if you’re curious, I usually get zero sales from these projects, but I’m not really in it for the money so it doesn’t much matter). Or you can just go grab a PDF above and print one out yourself.

The Power of Appearances

The other day I managed to pull off a fairly complicated Illustrator effect that I was rather proud of, and I wanted to share it today with all of you and talk about how I did it. While you may not ever want to reproduce this exact effect, hopefully it will give you an idea of the power and flexibility of a couple of my favorite parts of Illustrator: appearance attributes and knockouts. I talked about these two particular things in a recent post, and so if you’d like a little background, head on over there first. Here, I’ll be working from the assumption that you’re familiar with these concepts.

Quick Background

I have been working on a series of ecological maps for a client, and one of the things they show is the range of various species: either their total annual range, or their range for a given season.


The client then asked me to develop a way to show both at once, where the seasonal range edge overlaps the total range edge. So, this is what I came up with, and what I’ll break down here.



Let’s start with a blue dashed stroke. It my case, it’s 16pt, with 10pt dashes and 5p gaps. And I’ve set the dashes to align to corners and ends so that they look a little tidier.


I really only need an inside stroke here, rather than ones that goes on both sides of my path. But, you for some reason can’t do an inside stroke in Illustrator if you’re also using the “align dashes” setting. And I do want to keep the dashes aligned, because they tend to look a little nicer and more even in my opinion.

So, to work around that, I will add another stroke on top (9pt), this time solid and outside.


Then I’ll set it to 0% opacity, and turn on Knockout Group for the whole object appearance. So, now the outside portion of our dashed line is gone. If any of this is unfamiliar, I would again recommend reading this post, which will give you a hopefully-adequate sense of how appearance attributes and the Knockout Group setting work.


So, now I’ve got the blue portion of the stroke finished. Let’s add the grey portion on the outside. I’ll add another stroke, this one grey, 4pt, and with the same dash pattern.


Only the portion that’s inside the path shows up. The outer portion gets knocked out by that outside stroke we set up, above.

Here's what it looks like with the outside stroke turned off.

Here’s what it looks like with the outside stroke turned off.

Now, I want a little gap between the two strokes. Let’s start by creating a new, 0.5pt stroke. Color doesn’t matter, but I’ll make mine red to stand out.


Now, I use the Offset Path effect to shift this thing inward by 1.75pt.


And then I set it to 0% opacity. Since we’ve got Knockout Group on, it knocks out the stuff underneath, leaving a 0.5pt gap between our grey and blue strokes.


For the final portion, I want to make these dashes fade away as they get toward the center of the shape. I like the softness of the look, and to me it also imparts the idea of “the species stays on this side of the line,” which is important when the shape is large enough that the reader might not always be able to see the whole thing at once.

I start by adding a fill on top of everything, and offsetting it inward (2pt in this case). This means the fill doesn’t start until just after the gap. Right now it’s covering the blue stroke.


Next I apply a 4pt feather to the fill to cause it to fade at the edges. Make sure to add this feather after (below, in the order of appearance layers) the Offset Path effect.

And then I set the fill to 0% opacity. Because of the Knockout Group setting, the blue stroke fades out as the invisible fill fades in.


And that’s the effect! Here it is in use on an actual map:


It does not always look great when going around hard bends or corners, but I don’t generally have those in the situations where I’m using it, so I don’t mind. Dashes often get pretty tricky in those situations.


The nice thing is that this is all one object. You could achieve a similar look by creating multiple paths all stacked on top of each other, but by doing it all on one object, it’s more flexible. If the shape needs to change, you don’t need to update multiple copies, each with its different stroke styles.

Again, I imagine that you probably won’t ever need to reproduce this exact style. But I hope this step-by-step gives you some ideas as to what sorts of cool things you can do by messing around with appearance attributes, knockouts, and effects.

A #PractiCarto Archive

For the past few months, on Twitter, I’ve been posting brief practical cartography tips every Tuesday using the #PractiCarto hashtag. You can click on the tweet below to read a thread with my whole rationale, but the short version is: by keeping it short, it makes it easy for me to share, and it makes it easy for the reader to pay attention — and thus, I hope, there are more chances to share knowledge.

This blog post is simply meant to collect my own #PractiCarto tweets all in one place. A few colleagues have also made use of the hashtag, which is great and exactly what I was hoping for.

Stephen Smith has put together a little notifier that will send you an email every time someone uses the hashtag, so that you’ll never miss out on useful mapping advice.

My #PractiCarto Archive

Even Fancier Type Knockouts in Illustrator

As longtime readers may know, I’m a big fan of label knockouts — see my previous tutorial on the subject here. I’d much rather have stuff underneath a label gracefully vanish vs. stepping on it with a halo. However, the downside with the technique I usually use is that you actually have multiple independent copies of the label: one you can see, and one (or more) that’s being used to make the linework invisible. If you move/change one, you have to do it with all the others.


Note how the waterlines vanish to make room for Ardebil. Note also how I moved the visible label for Rasht, but didn’t move the copy of the label that was being used to mask the waterlines.

I’ve lately figured out an improved technique in Illustrator that lets me make labels that knock out map features underneath them, instead of requiring a second, separate knockout object. This means you can move a label, retype it, etc., and it automatically clears its own surroundings.

This technique actually doesn’t wholly supplant the technique in my previous tutorial, as it can’t be used in every circumstance (as we’ll see). But it’s pretty great when you can get away with it.
Before we look at how to do this, there are two pieces of Illustrator that we need to understand: the Knockout Group setting and appearance attributes. You can skip ahead if you’re familiar with these already.

Knockout Groups

Perhaps you’ve seen this little checkbox on the Transparency panel and wondered what it did.


May need to click (more than once) on the icon next to the word “Transparency” to get it to appear.

When you have two objects overlapping in Illustrator, it has to figure out which parts you can see, and which are hidden. So, we don’t see the entire red square below, because the blue circle is covering part of it. Illustrator has knocked out (made invisible) part of the red square. Remember, we’re not dealing with real physical objects, so for one thing to hide another, Illustrator has to figure out how to make a decision for each pixel on the screen (or page): “do I show red, blue, or some combination?”


If I turn the blue circle partly transparent, Illustrator figures out that part of the red square should show through, and then does some math to determine what color the overlap should be. If I turn the blue circle completely transparent, Illustrator realizes that the red square should completely show through.


The order of operations here is:

  1. Look at transparency settings for each object
  2. Then decide if any of the red square needs to be hidden, or have its colors mixed with the circle

Turning on Illustrator’s Knockout Group setting reverses this order of operations. First, Illustrator decides that the blue circle should hide part of the red square. And then it looks at transparency settings. So, if we made the blue circle completely transparent, Illustrator first hides part of the red square (due to the overlap), and then makes the blue circle vanish.

The end result is that the red square is being hidden by something that’s invisible.

I must credit Illustrator guru Mordy Golding for my understanding of how this stuff works. I don’t remember if it was a blog post or one of his tutorials that I saw which taught me this, but I’ve been getting a lot of mileage out of Knockout Group for years thanks to him.


So, Knockout Group is the first piece. The second is the Appearance Panel, of which I am a big fan (as anyone who has ever watched me work in Illustrator will attest). This thing is the heart and soul of Illustrator, and I really think it should be introduced on Day 1 of Illustrator 101. But most people I know encounter it much later on, as I did.

All your art in Illustrator has appearance attributes. Fills and strokes are the most common, but there are many other possibilities: drop shadows, transparency, blurs, etc. Anything that affects how your vector paths look is an appearance, and you’ll see it in the Appearance Panel.


You know those little circles in the Layers panel, one next to each object and layer? The ones that you probably thought were used to select things? They’re actually for selecting and viewing appearance attributes.


The reason there’s one for the layer is that you can apply appearance attributes to an entire layer at a time, in addition to whatever attributes its contents have. For example, I can draw a bunch of blue squares.

Mysterious Squares: Our Misunderstood Friends (I stole this joke from Marty Elmer)

Mysterious Squares: Our Misunderstood Friends
(I stole this joke from Marty Elmer)

Now, if I click on the appearance circle for the layer they’re in, I can choose to add a new stroke from the panel menu (or use the “new stroke” button on the bottom of the panel) and add a stroke to them.

And now my squares all have a stroke. If I select each one, Illustrator will say it doesn’t have a stroke — because the actual objects do not. The layer does, and it’s applying that stroke on top of whatever’s going on with the stuff inside the layer.

This distinction of applying appearance attributes to objects vs. layers is super useful once you get the hang of it. I’ll leave you to explore a bit (since I don’t want to drift too far from our initial purpose here), but here’s an example:


On the left, a drop shadow was applied to each object. On the right, a drop shadow was applied to the whole layer, instead.

Knocking Out Labels

Ok, so let’s put these two pieces together: appearance attributes and knockout groups.

Let’s make a layer for some labels, and type some labels inside of it.
Now, let’s select our layer’s appearance (that little circle by the layer name) and go to the Appearance Panel and add a stroke to our layer and make it any color you want; I’ll go with black.


That worked, but now a stroke is covering up most of each of our labels. So, go back to the Appearance Panel (don’t forget to re-select the layer appearance if you deselected it — I forget to do this all the time, even after doing this for years) and take the stroke and click and drag it until it’s below the word “Contents.” “Contents” means the stuff inside the layer. We’re telling Illustrator to draw this stroke, but draw it below the contents of the layer (all of our labels). The Appearance Panel has a layer order to it, and you can rearrange what stuff draws on top of what. So now everything looks good.


Now, let’s make another layer underneath our labels layer, and draw some lines or something in it. This is the stuff we want our labels to knock out. And finally, let’s put both of these layers into a master layer, so that we have one top layer and two sublayers (one for labels, one for the map stuff).


Select the appearance circle for the master layer, go to the Transparency Panel, and find that “Knockout Group” checkbox. Click it until it turns into a check mark. It’ll turn into a dash first, likely, but skip past that. I don’t adequately understand what the dash setting does, but I am led to believe it has uses which are very, very rare. So we can ignore it.


Now we’ve turned on Knockout Group, so that activates that reverse order of operations. The labels are on top of the other stuff, so Illustrator figures out which parts of that stuff are hidden by the labels, and then afterwards it will calculate any transparency. Since nothing is transparent at present, this has no effect. So let’s change that.

Select the appearance for the labels sublayer and go to the Appearance Panel. We want to turn up the transparency on that black stroke. So we need to select carefully. We don’t want to change the transparency for everything (including the labels). So in the Appearance Panel, click on the entry for the stroke to highlight it. And then go to the Transparency Panel and set the Opacity of that black stroke to 0%. It vanishes (as we would expect when something is totally transparent).


Not only did the stroke vanish, but so did the artwork underneath it. If you want to get much mileage out of this technique (and figure out your own variants and other uses for these tools), you’ve got to understand what’s going on. So let’s go through it again (since it can be tough to wrap your head around).

All of our labels have strokes around them because we edited the appearance for the label sublayer and added a stroke. Then we made that stroke invisible (0% opacity). But, since the top layer had Knockout Group checked, Illustrator looked first at the labels, figuring out that they were on top of and hiding the artwork underneath, then erased those portions of the artwork. Then, and only then, did it calculate transparency and realize that the stroke couldn’t be seen, and so made it vanish. It’s still there, acting as an invisible buffer that knocks out stuff underneath.

And it’s all live. The stroke is applied to the label layer, so it affects whatever is in that layer. If we add labels, or move them around, the knockout still works. We can also go in and change how big the knockout is. I can go back to the stroke that I added, for example, and make it thicker. I also usually choose the rounded corner join, as well.



So, that’s a little trick for labels that knock out the stuff underneath. It can’t be used in every situation. I have maps, for example, where I want some labels to knock out some map layers and not others, and some labels to not knock out anything at all, etc. That would be pretty tough to arrange using the above technique, and so I generally use my opacity mask technique instead. But for simpler situations, this is a really handy trick to pull out.

One additional quick example of this technique. My transit-style river maps have double lines for all the water courses.


To do this, I went to the Appearance Panel and applied a thick blue stroke to my paths, then a thinner black stroke on top, then made the thinner black stroke invisible, then turned on Knockout Group (in this case, on the transparency for the object, not the layer, since all of this is happening within one object). The thin stroke hides the middle of the thick stroke, and then vanishes.

I hope all this helps. The Knockout Group setting has a ton of applications, especially in conjunction with cleverly-set appearance attributes, so if you take a while to mess around and get an understanding of how it works, it’ll pay off in the long run.