Rheia: one final try at ground-up worldbuilding

[Tiluchi]

Hi all!

This isn't my first started thread here, and most of my other posts have been similar projects: working on worlds from plate tectonics on up, in order to have a reasonably realistic world geography. Have started this twice before here and stopped both times due to not being satisfied with the general realism of the world's geology or the direction it was going. Nikolai Hersvelt's amazing posts over at Worldbuilding Pasta were enough to get me to give it another try with the new tools that are available, and I've finally progressed far enough to be much happier with where this is going in terms of aesthetics and realism. Figured I would post my progress here in case the workflow is useful to others considering similar projects.

Previous attempts started with a present-day world map, and working backwards with plate tectonics to get something reasonably plausible. This works as far as it goes, but I found it difficult to justify present-day positions of continents and plate boundaries with any kind of detailed history. After a fair amount of frustration with that I turned to the Worldbuilding Pasta tutorial, constructing a complete geological history of a world for about 800 million years until the present day. That worked better from a realism standpoint, but it presented the opposite problem for me: starting that early means the world tends to take on a mind of its own, and I ended up with a final geography that I wasn't particularly satisfied with (unfortunately, I only realized this after almost a year of working on tectonics and then topography). For those who are somewhat agnostic about the final geography and/or don't care as much about realistic biogeography, this is probably still the best way to go.

Ultimately I ended up going with a little bit of a hybrid approach: I made a very, very basic sketch of how I hoped things would look in the present day, then did a GPlates history going back about 400 million years. I chose this for two reasons: first, because tectonic events older than this generally have little to no influence on present-day topography, meaning that I could still feel pretty confident about realism. Second, because this means only going through one supercontinent cycle, allowing me more control over the final geography while still giving lots of geological detail. It also allowed me to get even more detailed with things like terranes and microcontinents than the Worldbuilding Pasta example, close to how things worked on Earth. (note also that our understanding of Earth's plate movements older than 400 million years ago is sketchy at best, so I wasn't too worried about losing important details)

A gif of the last 420 million years of plate tectonics is below (sadly compressed to all hell to make it a small enough file for the CG site). I'm lazy and technologically inept so this is just a screengrab from GPlates, without a tracker of the number of years- just know that it starts at 420mya and ends at the present day.

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A few weeks of work on plate tectonics leaves me with the present-day map below. The little empty polygons in the middle of continents are cratons, black is active continental orogenies, orange is active volcanic orogenies (my worldbuilding requires distinguishing between igneous and sedimentary rocks in the present day), grey and yellow are former orogenies, purple is large igneous provinces, and light blue is oceanic plateaus. Obviously these are just guidelines (and the "continents" are actually continental shelf rather than dry land), and I still have a fair amount of leeway for making coastlines and topography for my liking.

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Currently I'm working on the topography of the world. It's probably not an entirely rational decision, but I'm opting for hand-drawing contour lines in Illustrator, rather than using Wilbur. I may force myself to learn Wilbur (the work of Harrg and MrBragg on here, among others, is inspiring), but for the world map I'd rather have control over the topography and placement of rivers myself, and have a vector-based world map that I can change or add details to later as I work on world history and other things. I'm also using Mac and suspect my work PC would just dissolve into a puddle of acid if I tried to use Wilbur on it.

Posting here my current progress, with two major continents finished and four more to go, plus most of the islands. It's a much-reduced PNG version of my 16000 x 8000 Illustrator image. I probably won't put quite as much detail into the other continents as I have into the largest one here, mostly because I know Lightroom has a tendency to crash when a file just as too many objects. I also expect there will be some minor-to-medium changes after I have a first draft of worldwide coastlines and elevation, and once I've finished climates and have a better idea of precipitation, currents, and erosion.

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Comments and critiques of the geology and what I have so far of the topography are much welcomed!

[Harrg]

It looks very exciting. I love following different approaches in worldbuilding. I like your approach with geological history and different kinds of rocks. Perhaps at some point I will borrow your results)))

[Peter Toth]

Hi Tiluchi,

Looks like exquisite work; much more involved than any I've ever done. Like you, I used the tutorials on Worldbuilding Pasta to create my tectonic history, although mine is so crude and sloppy I was embarrassed to show it with my main equirectangular map. I like your fully rendered terrain for the first couple continents, as it looks very realistic and convincing. How did you generate this terrain, if you don't mind me asking?

Are you planning to model this planet with Earthlike parameters or are you aiming for something different?

Again, looks fabulous! Will follow this thread closely.

Peter

[Ottehcnor]

I really like this - I've appreciated the recent posts with a focus on a more thorough world-building, as it gives me a lot more ideas about how to go about it.

Your final continents look great, and I especially like the grouping of islands just north-east of center. Islands are always the hardest for me to get right.

Looking forward to seeing your climate maps and your continued progress!

[Tiluchi]

Thanks all for the comments! Took a break from working on the map for a few days to pay attention to other hobbies, but about to start working on the next continent.

Hi Tiluchi,

Looks like exquisite work; much more involved than any I've ever done. Like you, I used the tutorials on Worldbuilding Pasta to create my tectonic history, although mine is so crude and sloppy I was embarrassed to show it with my main equirectangular map. I like your fully rendered terrain for the first couple continents, as it looks very realistic and convincing. How did you generate this terrain, if you don't mind me asking?

Are you planning to model this planet with Earthlike parameters or are you aiming for something different?

Thanks! Honestly, I drew the elevation map entirely by hand using Adobe Illustrator (I think other vector programs such as Inkscape would do a similar job), with a number of Earth topographic maps as a reference. It's a vast amount of work but I wanted complete control over elevation so I could easily make edits to the topography or add detail to certain areas at a later date. I highly recommend vector-based maps over raster-based programs such as Photoshop if you're planning to do very in-depth worldbuilding work, as it allows for a "master map" with much more detail and a smaller file size.

Ultimately I imagine this will follow Earth-like parameters, at least as far as climates go. I'm actually currently thinking this will be a moon orbiting a gas giant planet in the star's habitable zone, albeit not tidally locked due to magical/handwaving reasons. However, I still have to do a little more research to find out if this would necessarily impact climates or other things before I make a final decision there.

[Stìophan]

I absolutely love your map Tiluchi, it's an absolute inspiration. I agree with you totally in the vector v raster debate however, one thing I have found is that after having tried Inkscape and Affinity Designer, I can't seem to get the same level of detail as Illustrator, especially doing small ,minute contours, unless of course I'm doing something wrong!

[Peter Toth]

Hi Tiluchi,

I absolutely love tinkering with planets that are moons of gas giants in a star's habitable zone. In my previous project, I opted for a brown dwarf as I wanted some extra heating on the tidally locked side, just to make things interesting. The only problems I ran into were extreme tidal bulges even at more distant separations and larger massed jovians, which I used to my advantage. For example, with a 500 earth-mass jovian at a separation of 330,000 km from an earth mass planet, you'll get a 24-hour revolution period. This arrangement, however, will also give you a 50 km tidal bulge at the equator (provided adequate water depth) and an unavoidable tidal lock. I believe you can circumvent the tidal lock without magic, however. All you have to do is set the separation at 14,000,000 km, which will give you earthlike tides and not tidal lock for several billions of years. I have a rough spreadsheet to estimate values but it relies on approximations. As for climatic effects, the only thing you should be concerned about is a jovian's intense radiation belts, which would require plenty of protection in terms of magnetic field, rotation, or a dense atmosphere. To be honest, I'm not certain if I met these specifications on my last project, Kaunis.

[WoodytheClimateGuy]

Hey man, nice to see that you are doing worldbuilding and I love your project that you are working on. I am also using Adobe Illustrator, because I prefer its more precise nature, so do you have any tips to increase production and make it go faster? Also, when you eventually get to the climates, just a note that the pressure cells are not exactly the most correct. While it is true that the high-pressure zones are mostly near the cold currents, there are also low-pressure cells along with the high ones.

If you want an idea of how this works, here is a worldbuilding guide by Madeline James. If you are doing this, I like the WB Pasta guide, but for the creation for the atmospheric pressure cells, I recommend this for more accuracy.

Honestly, I am glad you are doing this because I want to see a more detailed take on their climates, specifically their temperature and precipitation. I know Charerg is doing one, but I'd like to see you do it. Good luck with your project!

[MrBragg]

This looks amazing! I would totally believe that your coasts and mountains were real places How long does it take you to do the topography on a continent the size of your largest here?

For your tectonics, how much detail did you go into during the course of the model? I found myself agonizing over plate interactions to the point where ~250 Ma took me years to get happy-ish with, so I want to know your secrets!

[Tiluchi]

I absolutely love your map Tiluchi, it's an absolute inspiration. I agree with you totally in the vector v raster debate however, one thing I have found is that after having tried Inkscape and Affinity Designer, I can't seem to get the same level of detail as Illustrator, especially doing small ,minute contours, unless of course I'm doing something wrong!

Thanks Stiophan! Good to know re: the other tools; that's not particularly surprising I suppose but it does make me feel a little better about shelling out the money for Illustrator.

I believe you can circumvent the tidal lock without magic, however. All you have to do is set the separation at 14,000,000 km, which will give you earthlike tides and not tidal lock for several billions of years. I have a rough spreadsheet to estimate values but it relies on approximations. As for climatic effects, the only thing you should be concerned about is a jovian's intense radiation belts, which would require plenty of protection in terms of magnetic field, rotation, or a dense atmosphere. To be honest, I'm not certain if I met these specifications on my last project, Kaunis.

Thanks Peter, that's very helpful! Question from a total physics newbie: would this distance make the planet look relatively small in the sky? That's about 14 times further from the planet than Ganymede is from Jupiter I believe. At any rate, I do think I'll go for magical rather than scientifically plausible explanations for it since that fits in well with the story I'm imagining at this point. Although I may change my mind, so this is good to know.

If you want an idea of how this works, here is a worldbuilding guide by Madeline James. If you are doing this, I like the WB Pasta guide, but for the creation for the atmospheric pressure cells, I recommend this for more accuracy.

Thanks Woody! I hadn't actually seen Madeline's work before but it's a very useful resource. I expect I'll be using some combination of the Azelor tutorial and the Worldbuilding Pasta tutorial for this, and this is another good one to add to the mix. I'm sure I'll read through her site later when I get past just doing the topography, but it seems all the different resources have their advantages and disadvantages, so more sources is always better.

This looks amazing! I would totally believe that your coasts and mountains were real places How long does it take you to do the topography on a continent the size of your largest here?

Thanks MrBragg! Your own work has been an inspiration for me getting back into this. I gotta be honest, doing this by hand is a LOT of work- I'd say a solid 3-4 hours per major layer in the largest continent, which is to say a solid couple weeks of long mornings just working on the little details. Still worth it for me and I'm very happy with the result so far, but only recommended if it's a world you expect to be dedicated to for a long, long time. I'm trying to do the other continents with a little less detail (50% zoom rather than 100% zoom), since I don't want to overload Illustrator as I've heard can happen, but so far it seems that that's still about 2 hours per layer, probably around 100 hours of work or so to get the whole world finished.

For your tectonics, how much detail did you go into during the course of the model? I found myself agonizing over plate interactions to the point where ~250 Ma took me years to get happy-ish with, so I want to know your secrets!

Oof, tectonics have been a major headache for me as well, and that's coming from someone who's fascinated by geology and reads articles about plate tectonics for fun. I think it took me about 2 weeks to finish this, but that's only after having gone through 900Mya of tectonic history for a different world (that I ended up scrapping in part because I wasn't satisfied with the geological accuracy). I did go into a fair amount of detail in the tectonic history, in part because reading about real-world geology has made me realize how much tectonics depends on the movements of a bunch of different microcontinents and island arcs- look at how the Mediterranean Sea, Indonesia, or Central Asia developed, for instance. If I was going to recommend any modifications to the Worldbuilding Pasta tutorial, it would be to do the world's history for less time (maybe 400-500 million years), but in more detail, especially for the past 250 million years or so. Mountain chains older than that have already been eroded away to nothing, and if you need to add some old orogenies to be uplifted, or figure out shear zones or lineaments it's probably fine to handwave them in anyway since you can guess where older active margins or orogenies would have been. Meanwhile, making recent or ongoing continental collisions messy affairs (again, look at the tectonic history of Europe or Southeast Asia) can be useful for getting more varied coastlines and more detailed topographies. Also, I elected not to worry too much about oceanic plates until about 250 million years ago, which is the age of the oldest oceanic crust on Earth, which saved me a huge amount of headache since that was by far the most frustrating part of doing the WP tutorial. Looking at reconstructions of Earth's tectonic plates it seems like mid-ocean ridges are frequently shifting and/or going extinct, so it's probably fine to give yourself a little bit of leeway there.

In general for figuring out tectonic history, I found Scotese's rules of thumb for plate tectonics to be a very useful guiding rule to complement the Worldbuilding Pasta tutorial. Specifically, keeping in mind that subduction zones are difficult to start and difficult to end was useful for not letting plate movement get out of control, as well as the reminder that mid-ocean ridges and subduction zones are most often parallel to each other and subduction is usefully orthogonal rather than oblique. It was also super useful to refer back to real-world tectonic history whenever I ran into conundrums- I would look for similar situations in Earth's past and either use that as a model or if I couldn't find anything similar, it was usually a hint that I got something wrong. GPlates actually has sample .rot files and shapefiles that go back through about 400 mya of tectonic history, which I was constantly referring to. If nothing else it's a reminder that all but the most recent plate tectonics are mostly guesswork so it's alright to let yourself off the hook if you're finding oceanic plates overlapping when they shouldn't or whatever. Apologies for the long-winded answer- I've been through this a couple times so far so I'm happy to chat more. I've been wondering if it's worth starting a Discord or something specifically for these bottom-up worldbuilding now that there are a number of us doing it, so that it's easier to share WIPs and tips and tricks for the process.

Also sharing the latest WIP, as I have to take a hiatus of a week or two thanks to work-related travel. Only about halfway through the second-largest continent (everything 750 meters above sea level and below), although I have a decent idea of where the proper mountains will go at this point. I've been debating whether to make that inland sea a true endorheic basin like the Caspian Sea or to have it draining through a deep canyon like I do now. The former is probably the more realistic choice, but the latter seems more fun from a worldbuilding standpoint- a river draining a huge inland sea isn't really something we have on Earth but it's cool to think about. It's also not completely far-fetched, as we have big gaps in continental volcanic arcs like the Columbia River Valley, and there's already some rifting in the center of the continent that could potentially travel down to the southern coast. Still debating though... perhaps I'll wait to see what the precipitation is like, as if it proves to be a huge desert perhaps an endorheic basin would make more sense.

Also note that I'm for the most part only doing the continents for now and saving islands for last- mostly because islands are the most fun to draw for me so it's nice to have something to look forward to

As always, critiques and comments are welcome!

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