Greetings everybody,

For a long time now I've been desiring to see a terrain generator that relies on plate tectonics. The projects that have such a goal seem to be few and far between, so it seems that it's too difficult to do or that the approach is too unpractical when compared to more artificial/direct methods (like fractals). In any case it seems like it's not a very popular topic in the (hobbyist) game programmer scene. A quick search on the GameDev forums gave only one topic that uses plate tectonics (it was posted two weeks ago) - Carradine described in his "Vantage: Prehistoric Simulation Game (online) - Pre-Alpha" topic that

You use a “plate tectonic simulator” to design the initial creation of the world, which places mountains, plains and islands in the world by simulation millions of years of tectonic movement, then edit the specific placements, use temperature terraforming and moisture algorithms.

It would be interesting to learn more on his plate tectonic simulator and the way he uses it to create worlds, but in any case this seems to be the only game that utilizes plate tectonics. To find out why it is so, I decided to try to make terrain with plate tectonics myself.

For my bachelor's thesis (that I started some 10 months ago) I made a simple terrain generator that loosely mimics plate tectonics. It starts with a flat fractal generated terrain that is randomly split into plates. The plates are moved linearly until they grind to halt due to friction. Sometimes plates overlap i.e. collide. If the overlapping portions of the plates are continents and there's "too much" overlap, then the continents are merged together. If oceanic crust collides with any other plate, the sea floor "subducts", meaning that the subducting crust is moved from the denser plate onto the overlying plate. After the rate of action on the "lithosphere" drops too much, the terrain is split into new set of plates and the process just described is repeated.

The results are rather good considering the simplicity of the implementation:

[attachment=8099:tectonics_ultim3.png]

[attachment=8101:tectonics_ultim6.png]

[attachment=8100:tectonics_ultim5.png]

The thesis is freely downloadable from http://urn.fi/URN:NB...mk-201204023993 .
There's also a Youtube video showing the simulator in action:

Lastly, the source code is distributed under GPLv3 in SourceForge: http://sourceforge.n...rojects/platec/

It seems to me like even the most naïve model of plate tectonics is able to produce more convincing heightmaps than conventional fractal based methods. That's why I'm really wondering why it's not used in more projects? And as a continuation to that, what would be needed for plate tectonics to make its way to the game industry - or is it worth it at all?

So, what do you think?

It seems to me like even the most naïve model of plate tectonics is able to produce more convincing heightmaps than conventional fractal based methods. That's why I'm really wondering why it's not used in more projects?

Fractal-based methods are often used because it is fast enough to be computed on the fly for procedural terrain (see Minecraft). For extremely large scale terrain you simply can't have all of the terrain in memory (see I-Novae). This is the main reason why fractal-based methods will continue to be very popular.

Your work looks awesome. I don't have time to read your thesis though. Do you have any rough numbers on how long it takes to simulate and what resolution height-maps it can run in reasonable time?

Colinhect,

The thesis contains a table of measured running times and (horribly unoptimized) memory usage per map size (chapter 8.2 or page 55). The running times are

• 8-15 s for 128*128 map,
  
• 25-37 s for 256*256 map,
  
• 70-140 s for 512*512 map and
  
• 300-480 s for 1024*1024 map
  

on a Pentium 4 CPU. So, adding even more size and detail would mean hours of running time per map. That forces the map generation to go offline. However, I was thinking that the output from tectonic generator could be used as a template for fractal generator. E.g. take a 128*128 map, scale it by 4 and fill 75% of the map with such fractals that they preserve the original 25% of the heightmap data ("corner points"). This might result in very detailed maps that have quite realistic landforms very fast. But, i haven't tried it out yet. Should'nt be too difficult to do. If there's interest, I might try to find time to do it and tell you how it turned out.

The a "infinite world" kind of game mentioned by Bacterius never crossed my mind when I was thinking about where to apply plate tectonics based terrain generating. Unless someone comes up with a way to segment the world into separate tectonical entities that can somehow be vowen together when its needed (FYI I think it's not possible), then the only option is to generate an entire "infinite world" at once using "infinite amount of memory".

Maybe there's a way around this, but like I said, the project never aimed there. IMHO fractals are for those who desire infinity.

However, I was thinking that the output from tectonic generator could be used as a template for fractal generator. E.g. take a 128*128 map, scale it by 4 and fill 75% of the map with such fractals that they preserve the original 25% of the heightmap data ("corner points"). This might result in very detailed maps that have quite realistic landforms very fast. But, i haven't tried it out yet. Should'nt be too difficult to do. If there's interest, I might try to find time to do it and tell you how it turned out.

Outerra renders an entire planet using real-world elevation data for low-resolution and fills in details using fractal algorithms. I believe they are interested in eventually supporting completely procedural planets as well. The low-resolution data could easily be generated using an algorithm similar to yours to provide more realistic continent-level terrain while still providing details via fractals.

In fact, I'm sure this would generate some interest by the Outera devs and community if you were to post this in their forums.

In fact, I'm sure this would generate some interest by the Outera devs and community if you were to post this in their forums.

I wonder if they would warm up for a redirection here. I mean it doesn't feel good idea to spread this topic all over the internet, especially when the discussion has calmed here, so maybe it wouldn't be such a big etiquette blunder to go to their forums and tell them to come here?

Hey, I found this thread by googling for "procedural tectonics" I read through your thesis a bit and found it really interesting! It was cool that you distilled all of the information on Earth science I've been trying to absorb the last few days.

I would have liked to see a lot more examples like Fig. 24. Maybe you could post more in this thread? Your results are pretty fascinating.

Thanks for sharing your work, it's very helpful!

I would have liked to see a lot more examples like Fig. 24. Maybe you could post more in this thread? Your results are pretty fascinating.

Thank you so much for the positive feedback! I'm especially joyful to hear that you enjoyed the theoretical portion of my thesis - I put a lot of effort in it because I wanted to produce a comprehensive yet easy-to-read introdution to the theory of plate tectonics. I hope it helps you and many other people interested in this topic!

What comes to new screenshots I must disappoint you for a moment. The pictures visible here and especially in sourceforge.net pretty much cover the most interesting aspects of the simulation/terrain generator. I am currently making some adjustments to the code - addings super simple river erosion simulation, improving subduction, making the output more rough to improve the natural look and feel of it... But I've been super busy, far more than I'd like, thus I haven't been, and in few weeks still won't be, able to share anything with you. But just wait... !