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!

15 thoughts on “Towards Less Blender-y Relief

  1. I’m coming from a different perspective. I design maps as a graphic designer. I don’t use GIS or blender. But I couldn’t agree more.

    1. I would expect so. You’d just run a mean smoothing pass on the DEM, then do some map algebra to mix it back in with the original DEM. I have noticed that doing focal statistics in GIS tends to produce slightly different results than blurring in Photoshop, for example, but I expect that’s down to something about how each pixel is weighted, which is something that I believe you can mess with at least in Arc and probably somewhere in QGIS as well.

  2. Yep, agreed Daniel. Thanks for putting to words and illustration something I’ve had blendering about in my thoughts but not brought into the foreground enough to articulate clearly. Now I’m reliefed.
    And the theme song: (which is fun and energetic, but after awhile on repeat leads on to start looking for other things… Hmmm, a theme.)

  3. I took a stab at matching the look of a USGS map with hand drawn relief using rendered relief. It was fun. Definitely did some smoothing and turning down the exaggeration. Sometime in the last year, I experimented with a tool in either GIMP or QGIS that allowed me to separate the DEM into a variety of resolutions. Damned if I can remember what it was now though.

    1. I went back and looked for the tool I used. It’s “split details” in the G’Mic plugin for GIMP. I combine the render from Aerialod with the map in GIMP. Splitting the details of the render and then adding different levels of detail is a fun way to experiment with the level of detail the looks right. I forgot about this. Thanks, Daniel.

  4. This seems to work well on land locked areas, but along a coast or with islands, the blurring causes the land to bulge up past a coast. Have you found any way to deal with this beyond painstakingly using a 100% clone brush just along coastlines?

    1. You can use a land/water mask to clip the relief, which should solve that. Even if the relief is artificially cut off this way, it’s often not really noticeable on the final map. Alternately, you could clip the DEM before making a relief, and put a little dark glow on the mask so that it basically fades the DEM down as it approaches the water. I think either of those two things have worked for most any situation I’ve encountered.

      If you do want to go the clone brush route, you might save time by doing content-aware fill, instead. I do that with small gaps in land cover (where my land cover dataset doesn’t quite align with the shape I’m using for my ocean, for example). Select a band of pixels that go a short ways out into the water, and then apply a content-aware fill, and Photoshop should supply something reasonable that would be much like a clone brush, but won’t require manually repeating it.

  5. I believe just duplicating the DEM layer in PS, adding some Gaussian blur and reducing the opacity to some level (90% you say on the example?) would do the trick?

    1. I expect so. This is pretty much what I do, though I carry it out in Blender usually, but it’s the same thing — a blurred and an unblurred version of the DEM, each mixed together at whatever ratio looks pretty good to my eye. Often around 9:1 or 8:2, though it can vary. I believe the method I linked from Tom Patterson might be a bit different just because it’s tied to a much older version of Photoshop.

      1. How would you make the blur in Blender, if I may ask? If it’s a quite straightforward process, I’d gladly skip the intermediate step in PS :)

        1. Actually, I do the blur in Photoshop and mix the two versions in Blender. I would love to do the blur in Blender, but, unfortunately, I don’t think it’s possible with the base state of the software (though maybe there’s a script/plugin?). I poked around at this at one point but couldn’t find anything. Blender will let you blur an image *after* it’s rendered, but image textures are generally imported and used as-is.

  6. To some extent I think this is about two different things: maps as information vs maps as art. The Scotland map above would make for a lovely wall print – a modern take on a classic mid-century aesthetic – but it’s borderline useless if you actually want to find something out about Scottish topography or geology. I don’t think that was the point of its creator though.

    1. Very true. I think a lot of terrain maps fall into the “for art purposes only” category, Blendered or not. I would argue, though, that if that’s the goal, making use of an old geologic map as a base might not be needed. Old maps have their aesthetic value, and shaded relief has its aesthetic value, but to my taste, it feels like they’re getting in each others’ way. And part of that is probably just my opinion that the “add relief to an out-of-copyright map” fad is way overdone now. It was interesting the first few times I saw it, but there are seemingly hundreds of shops that sell them now. But, again, that’s all about my taste.

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