I'd like to ask a naive question, as I'm not really familiar with procedural terrain generation but I've been curious about it from afar. From what I can tell, most work in this area revolves around manipulating geometric patterns to "look like" mountains/islands/whatever.

Is there any value in modeling geological processes instead? So if you take a flat plane, along with a model of geological forces that could alter that plane, and run some kind of simulation over time (in effect simulating erosion etc), could that not produce a more "realistic" terrain?

I assume it's much more complex, much more computationally expensive, and all that. But I'd be surprised if no one at all has attempted this.

Well, the article does mention that Part IV adds erosion. Note also that this particular source is a rare example of working based on a mesh rather than a grid (which complicates the logic - in particular, when do you split/merge nodes? - but should be cheaper at scale).

People can try something fully physics-based (or rather, physics-inspired) even for earlier stages, but there are problems:

* You still need some kind of nondeterministic input so you don't always generate the same world.

* You must do the whole world at once, rather than being able to generate each area independently.

* This requires the computation to run for a long time, and needs to feed back in on itself (think of "lake overflows a natural dam and carves a valley, then the tectonics lift it and change the low point anyway").

* It's very easy for your code to result in "boring" outputs, such as "all flat" or "infinitely deep valleys".

There's been a fair number of previous posts which cover that topic:

https://www.google.com/search?q=news.ycombinator.com+procedu...

This one is a particularly useful starting point: https://news.ycombinator.com/item?id=5196154

The extremely accurate and high end terrain generation tools do exactly this. They model different terrain densities, erode-ability, and permeability to then apply rain, snow, tectonic shifts, river erosion, thaw-melt, etc over virtualized eons.

The result is incredibly detailed terrain that is completely unique based on the initial parameters and the randomness of the time-elapsed process that is non-deterministic.

The only downside is that it takes hours to simulate and that's more than most folks are interested in investing in.

Here are some examples of this kind of software:

World machine: https://www.world-machine.com/

Terragen: https://planetside.co.uk/

Vue: https://www.bentley.com/software/e-on-software-free-download...

Gaia: https://www.procedural-worlds.com/products/indie/gaia/

You might be interested in this read from the procedural generation wiki: teleological vs ontogenic. This style here is ontogenic, teleological involves simulating more of the processes. http://pcg.wikidot.com/pcg-algorithm:teleological-vs-ontogen...

It'd be neat to see a game world where the simulation remains ongoing, where the world is actively changing.