July 18, 2018

Elevation V: I Want to See Mountains Again!

I've put the endorheic code aside for now. It's making everything much too smooth.

Instead, I'm trying to fit the original tectonic faults back into the system. The map from the endorheic basins post was one such map.



The keys here are fiddling with the original maps and with the uplift map, which determines how much the land is affected by the tectonic collisions.

For one thing, I need to add more plates, now that the system is a little more extendable. I don't really want to mess with the coastline, but right now the terrain is really boring on a couple of these continents.

The other thing is adding a factor to push the coastal hexes down towards the sea. Otherwise, hexes with no appreciable drainage (islands) end up being the limiting factor (the erosion cycles run until one of the hexes maxes out at 25,599 feet).

I can also start with some white noise as the initial map (instead of designing them by hand) and see where things lead. Remember that erosion is partially a function of rainfall, and I painted those maps using the original height maps. I should probably paint them based on the uplift map (which is based on the fault lines). Here Dragons Abound did something very similar, although there are enough slight differences that it's worth tackling from scratch for me.

Since I don't have a way (yet) to model the force of collision, I will simulate folds by assigning an uplift scaling factor $u$ based on the distance to the fault line $f$ and distance to the coast $d$.
\[u = \left(\exp\left(-f \over 500\right)\cdot\left(1 + 0.1\cos\left({2\pi \over 100} f\right)\right) + 0.1\right)\cdot\left(0.9999\left(1-\exp\left({-d \over 20}\right)\right) + 0.0001\right)\]
Simple.

That yields this as the initial uplift:


So the mountains should grow out of this after enough cycles. Man, I really should add more tectonic plates. There's an entire continent there (top/bottom left, I really should assign some temporary names) with very little tectonic activity.

When I was writing this post, I intended to come back and show the result of that map. But I tried something else instead. I added a little bit of Perlin noise to the uplift map. Now this could be something interesting.


Can't tell that much difference. But it's nice to "salt" things a little.


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