A Generalization Ramble

Spatial accuracy is not always your friend.

A few weeks ago I wrote about the potential downsides of making an overly-detailed shaded relief image. It’s easy for readers to miss the major landforms, as they are hidden under the highly-detailed noise of the individual hills and bumps.

I truly understand the urge to show all that detail. It can feel wrong to hide it, to smooth it away, to present a gross reduction of nature’s amazing complexity. We are awash in so much great data nowadays, so let’s show off all of the exquisite detail that we finally have about land and water and populations and incomes — information that previous generations would have loved to access, but couldn’t.

But more importantly, it feels safer. 

Putting every possible detail on the map means we can avoid difficult choices about what to show and what not to show. We can tell ourselves that we’re just showing what is, without applying influence. We can say to the reader “I’m just putting everything out there and you can decide; I’m not trying to interpose myself.” It lets us imagine that our maps are objective, even if that’s not actually possible; nothing authored by humans (or authored by human-authored software) can be anything but subjective.

If we don’t make too many choices, hopefully it also means no one will disagree with us. Map generalization is a form of artistic vulnerability. If I reduce the detail in a coastline, I am keenly aware that another person might have done it a bit differently. Did I do it wrong? Should I have used different parameters? How much is too much? Does mine look stupid, or confusing? I grapple with this constantly.

We all commit sins against the landscape when we fix it into a cartographic form. I know that it can feel uncomfortable; it does to me. But it’s necessary if we want to serve our readers well. Think again to the example above, of the broad landform structures vs. the tiny details. The “right” answer will depend on the map that you are making, but in many, many cases, it’s better for the reader to focus not on the thousands of individual peaks and valleys, but the great ridges that they form — the large structures that affect the weather, determine the course of streams, and constrain the movement of animals and people.

Here’s an example I often share with students. Fictional cities, in a fictional country (but based on a real-life example I encountered as a student).

Notice how Border City appears to be just inside the country of Pineland. But, if we make the dots semitransparent, you can see that, due to a dip in the border, Border City is actually in Utopia.

One easy solution is to just move Border City. I mean, you could restyle the dots, too, but if you don’t feel like doing that, just move things.

When I tell students this, I wonder if some of them find it shocking to hear. I think a lot of us, early on in our careers (certainly my own), are very attached to the idea that we must make maps “accurate” and “objective,” and so this sort of generalization feels very wrong. But sometimes the lie is more accurate. The reader now will correctly understand what country Border City is in. Just like, with the terrain example above, they will now correctly understand the big shapes of the earth, rather than getting lost in details that are technically accurate but serve no greater purpose.

I tell my students to contrast “spatial accuracy” with “narrative accuracy.” Instead of obsessing about the exact proper position of everything, the latter focuses on asking: What will the reader actually learn from the map? What will they remember five minutes after they’ve put it down? We’re generally not landing spacecraft with these maps, so it’s OK if something is gently smoothed or nudged (or even made up!), so long as it’s not so extreme as to leave people with the wrong impression.

It’s been a long journey, but I mostly do not hesitate anymore to move or reshape cartographically inconvenient features. Many times, though certainly not all of them, it doesn’t matter if you get it “wrong.”

This post ended up being a bit of ramble, much less structured than I usually try to present my thoughts here. Thanks for coming along!

Towards Less Blender-y Relief

In the years since I stumbled across the idea of creating shaded relief in Blender, I’ve been amazed at the extent to which the cartographic community has adopted this technique. This was wholly unexpected: I’ve seen plenty of relief tricks come and go without achieving widespread adoption. This makes sense, given that there’s no “right” way to do terrain — it’s all down to your personal taste. But, for whatever reason, Blender has stuck, and I’m gratified to see that.

And now I’m here to push back on Blender relief. Or, rather, I’d like to make an appeal: consider making your Blender relief less Blender-y.

As more and more people adopt Blender, I have begun to notice that many relief images made using this technique have a fairly common look. Here are a few examples I found by looking at Reddit posts that linked to my Blender tutorial (worth clicking to see in detail):

(Sources: Iceland by u/EncompassGeographic, Imperium Romanum by u/boytutoy, Mediterranean by u/Xamos99, and Scotland by u/irishliam)

Notice the dark, dramatic shadows, and the highly detailed, very bumpy land surface in which each individual peak and hill sticks out. They all have what I might call the “Blender Look”: exaggerated terrain that almost looks cinematic. I’m not calling any of these particular authors out — they’re just handy examples of a widespread style trend. Interestingly, though, there’s nothing intrinsic to the Blender method that requires reliefs to look this way. Here’s one that I made in Blender that doesn’t have The Look (it’s also got a subtle hypsometric gradient blended in):

I’m not wholly sure how The Look came about. My suspicion is that the Blender’s particular strengths just steer cartographers in that direction by default. Blender is amazing at generating realistic shadows, and if you’ve just come from years of making more rudimentary hillshades in GIS software, that’s really attractive and interesting to play with.

Now, maybe you like The Look. It’s quite trendy in present-day terrain mapping, and I’m assuming that’s because many people find it attractive. Maybe that’s also why there are an innumerable number of shops out there selling prints in which someone has attached a Blender relief to an out-of-copyright reference map.

But I’m not really a fan of the Blender Look. If you are, that’s fine: keep making what you enjoy, and what your clients/customers/employers like. I may have helped to popularize the Blender technique, but it’s not my place to tell you how to use it. However, I’d like to offer some of my thoughts about how to get different-looking outcomes from Blender. Maybe you’ll like them, maybe not. The more alternatives you know about, the more variety you’ll be able to bring to your work.

Smooth It Out

My first concern about the Blender Look is that I often find it too detailed. Shaded relief of any sort can fall into this trap, whether made in Blender or not. Here’s a screenshot from the Shaded Relief Archive comparing a manual relief and one made using a standard hillshade algorithm from a GIS program.

According to the website, the manual relief “provides a clearer picture,” but really, that’s not because it’s manual, it’s because it’s simply more generalized. In the image on the right, you see many small mountain bumps — every detail of the terrain is captured. On the left, everything’s been smoothed out and you see the larger ridges that those bumps form. Oftentimes (whether we’re dealing with terrain or other datasets) the small details can obscure the bigger picture, and cartographers can help readers by aggregating those details.

Here’s a Blender-based example. Two reliefs of the same area, made using the same program and settings, but with different levels of detail in the underlying elevation data:

Notice, again, how the big terrain structures are more apparent in the image on the left. I’ve circled an area that exemplifies what I mean by that — you can click the image to see a larger version. On the right, we have just a bumpy texture. On the left, we can see the specific ridges and mountains that those bumps belong to.

For fun, here’s a snazzier version of the comparison, which I made to promote this post on Twitter.

I think that the less detailed relief is more suitable for a lot of purposes. It’s probably better, for example, for communicating the basic landforms to a reader — letting them see the big picture, without the details obscuring it. It’s also less noisy: without all those little bumps, it takes up less attention, meaning it works better as a background, where we usually don’t want many distracting, rapid changes in contrast (i.e., edges). Backgrounds are also areas where fine details aren’t noticed as well, anyway, so it’s probably best to keep things general.

I suspect that highly detailed terrain became part of the Blender Look because many mappers switching to Blender were used to using detailed DEMs as part of their process. The standard GIS hillshade algorithm doesn’t produce dramatic shadows, and it consequently doesn’t produce nearly as much noise when you’re feeding it a high-resolution DEM. Here’s the same DEM rendered in a hillshade, vs. in Blender:

Obviously you could tune the parameters in each of those to get slightly different looks, but you get the idea: Blender can make details stand out more, so if you’re not used to that, it can lead to things looking more chaotic, in my opinion. Of course, even GIS hillshades regularly need some simplification, but I think Blender often needs it more.

Here’s the simplest method to reduce detail: blurring. If you take your DEM and apply a blur filter in Photoshop/GIMP/etc., or you use a mean filter via a neighborhood statistics tool in GIS, you’ll start to merge those tiny bumps into the bigger structures. Do this to your DEM before you make your relief, not to the relief you’ve already made.

Now, that look can be a little too soft for some tastes and some mapping situations. There are ways around that. On option is to play around with other raster generalizations, such as median filters in GIS or image editing software, or a combination of mean/median filters, or other noise reduction tools available in programs like Photoshop. This isn’t a tutorial per se, so I’ll leave that idea for you to explore.

But I will give a plug for the method that I use most often to get around the soft look: resolution bumping. This is a technique by Tom Patterson with a basic idea that is simple but powerful: smooth out your DEM, then add back in just a little bit of the original, detailed DEM. This gives you the clear landforms of the smoothed version, while also giving you some visual texture from the detailed version. It’s definitely worth trying. Below, I took 90% of the smoothed DEM, and added in 10% of the full-detail DEM, to get something that looked good to my eye.

Again, my personal issue with the Blender Look being too detailed isn’t intrinsic to Blender as a program or a technique. Cartographers have long struggled with how to make digital relief that looks neither too detailed nor too soft, and many mappers have their own recipes for combinations of mean/median filters, or mixing different levels of smoothing, or other software trickery, to get things just right. And all of these ideas predate Blender relief. However, I think Blender relief is particularly in need of the application of these kinds of smoothing techniques, because it is simply more likely to produce a noisy result from a high-resolution DEM.

Less Exaggeration

The other aspect of the Blender Look, besides high detail, is its dramatic shadows. Every peak is separated by a deep black chasm, and every mountain stands impossibly tall, blocking the sun for large swathes of terrain behind it. Again, this is all very cinematic. But it’s not my preference, and maybe that’s simply because I’ve seen a lot of it over these recent years.

I think that, if you’re used to the somewhat more pedestrian GIS hillshade algorithm, the shadows that Blender can generate are exciting, and there’s a temptation to make them front-and-center in terrain work. I definitely get that — it’s much like any time we learn about a new tool: we want to lean into it and show it to our audience.

If your terrain needs to play nicely with other things (labels, water, roads, etc.), consider toning down the vertical exaggeration some. This is just a matter of changing the displacement scale in Blender, as seen in my tutorial. A little exaggeration can go a long way, but too much can blow out the rest of your map. Even if you’ve adjusted the particulars of the light-to-dark gradient used, to ensure that it doesn’t make your map too dark, an overly exaggerated relief can still make it seem more like you’re drawing text/lines on top of an aerial photo, rather than embedding them in the map.

Getting vector and raster to play together can be tough, and the more exaggerated and shadowy your terrain, the farther apart the vectors and rasters can feel. I speculate that this is because vector components are unaffected by the shadows — the terrain has shadows cast upon it, but the vectors don’t, and so the more shadowing you have, the more and more the vectors float atop the landscape rather than feel integrated with it.

Even if your relief is standing by itself, not having to work with any other layers, extreme exaggeration can still be detrimental. Those dark shadows are hiding parts of the terrain.

What’s going on in the circled area? The version on the right makes it much harder to tell.

I think terrain relief is much like a lot of other cartographic effects like glows, haloes, drop shadows, etc: they often work best when they’re subtle enough that people can’t tell they’re there. I think the urge to crank these effects up comes from a concern that readers won’t perceive the effect. But they will: it takes less than you think for the effect to work.

Make What Looks Good to You

The Blender Look isn’t to my taste, and if you love it, or you love it under certain circumstances, go for it! I’m not here to shame you for your preferences. I wrote this because I thought that maybe some people have been steered into The Look without thinking about the alternatives. So I hope you’ll take it that way: just a few thoughts on other ways you can make your relief look, if you want to mix things up.

Shaded relief doesn’t always need to be dramatic. You might like that look, and it can be serviceable in some contexts, but I think it’s valuable to have a few other styles in your toolkit. Blender can help you achieve those, too. There’s a lot of amazing terrain on this planet (and others), and I understand the urge to try and throw a lot of detail at the reader. All I ask is that you take a moment to weigh much they, and the rest of your map, can handle.

If you’d like to support essays like this one, one of the easiest ways you can do that is to spread the word — tell your friends and colleagues about my tutorials, YouTube videos, or whatever else you think they may like. And, if you’re interested in lending financial support to my effort to remain an independent teaching cartographer, I have these two handy buttons for you!

Annual Report: 2021

Friends, colleagues, and patrons, it’s time for my Annual Report. You’re all so kind as to support my work each year with donations and with spreading the word, and I try to be transparent with you about what exactly you’re supporting.

This year it felt like I had a lot less time to devote to side projects and tutorials. Maybe that’s just my perception, and it’s not actually true — it’s been a confusing year for many of us. But in whatever quantity I was able to, I’m glad to have been able to give back to the community that has taught me so much, and to repay your faith in me. With your support in 2021 I was able to (in no particular order):

Organize a mapping exhibit at the Overture Center, here in Madison. My colleague Tanya Andersen and I assembled a group of maps to help show the people of our area just how much cartography is connected back to our community. This is actually something that’s been in the works for a couple of years now, and we’re so pleased that we could finally make it happen. It’s up through January 16th if you happen to be in Madison.

Organize a special NACIS Map Gallery exhibit in Oklahoma City, Map Where your Heart is. It was great to see people share maps of places dear to them!

Answer a lot of questions via email, Twitter DMs, YouTube comments, Slack, etc. I spend a lot of my pro bono time out of the public eye. People write to me each year asking for software help (especially Blender), career advice, interviews for school projects, etc. I try to take the time to write back to everyone. It’s not really something I’d considered, when writing tutorials: the more resources you put out there, the more of these kinds of interactions they generate. I’m happy to help, and will try to keep up as long as the the volume remains manageable.

Volunteer to teach a class at UW. Tanya Andersen and I teamed up to run an independent study class at the University of Wisconsin. We met weekly (remotely) with our three students, advising them as they developed projects and carried them through to completion. This is some of my favorite work — being able to show people, hands-on (virtually) how to accomplish practical cartographic steps, and then watching them make great things with those tools.

Continue my “Live Carto” series from 2019–20, with four new broadcasts. It’s been fun to be able to work on a project and have people there alongside me to keep me company, especially during this pandemic isolation. I’ve appreciated being able to meet people from all over the world, and to be able to share knowledge with them in this format. I’ll continue doing this on occasion in the coming year!

Keep my tutorials updated. As software changes, often these resources need updating to stay useful (it can be frustrating and confusing to read through a tutorial that doesn’t quite match what you’re seeing on screen). I recently upgraded by Blender tutorial with new screenshots and workflow adjustments in response to that program being updated.

Create new tutorial content. Besides keeping old things updated, I also want to keep making new things that help people. This year I put out a tutorial on background blurring, and one on making semi-randomized dot patterns.

Create non-tutorial musings. That background blurring tutorial pushed me to consider some larger concepts that ended up as both their own blog post and a NACIS presentation.

Release short, ephemeral tutorials. It occurred to me recently that I also post mini-tutorials on Slack groups and on Twitter — things that don’t make it onto my blog or YouTube. These usually happen because someone asks a question about how to get something done, or because I discovered a neat trick I want to share, but it’s too short to be worth a formal writeup. Maybe someday I’ll collect these into a blog post.

Create a bunch of random one-off mappy things that get released to the winds of Twitter. Last year, I collected some of them into a free PDF book, An Atlas of Minor Projects. I haven’t done enough of these projects for a second book yet, but I am keeping track of them better this time around, so that maybe in 2022 or 2023 I’ll be able to assemble a second volume. Here’s one of those minor projects for you: a Halloween-themed map of the Murderkill River, in Delaware.

Make some non-live video content. I’m continuing to try and grow my tiny corner of YouTube. Besides the dot pattern tutorial, I also put together a walkthrough of how I make my cyanotypes, since it’s prompted a lot of questions from curious folks on Twitter.

I promise that I do not have that beard anymore.

Continue my long tradition of pitching in to help NACIS, the main professional society for mappers in North America. It’s an all-volunteer organization, so the more we all help out, the better it becomes. In the last year I:

  • Served on the Diversity & Inclusion subcommittee
  • Served on the Nominations Committee
  • Helped oversee logistics details for getting reprints of the first three volumes of the Atlas of Design to customers
  • Served as guardian of our projectors. I keep all four of them in Madison, and make sure they get to the conference site and back, without losing too many cords and connectors.
  • Co-led a special presentation with NACIS Past President Leo Dillon, in which we helped people better understand how the organization functions and how to get involved.

Present to various conferences and classes. Besides sharing some of my thoughts with the NACIS crowd as usual, I was also invited to present to WLIA, as well as a colleague’s class.

So, maybe it wasn’t as quiet a year as I thought!

Your patronage helps me justify taking time away from my freelance work in order to write, design, and help others. It also pays for things like conference fees, the fees I pay to keep ads off my blog, domain names, and other direct costs associated with all these side projects. Thank you for making this list possible!

As we move into 2022, I hope to continue to merit the support you have shown me. I never know exactly how much I’ll be able to do so in a given year, but I do know that I fully intend to keep up my efforts to contribute to the cartographic community. You have all taught me so much, and I will continue repay the favor as best I can.

If you’d like to support my ongoing work, one of the easiest ways you can do that is to spread the word — tell your friends and colleagues about my tutorials, YouTube videos, or whatever else you think they may like. And, if you’re interested in lending financial support to my efforts in the coming year, I have these two handy buttons for you!