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Recreating Rolling Terrain

Rolling terrain follows a specific pattern when viewed from the air. Anywhere on Earth, it is easily recognisable by the way it flows as a near never ending series of similar forms. Smooth, rounded ridges interspersed by valleys, leading down to deep valleys at either end.


An aerial photo of Gabilan Mesa, California shows off the rolling terrain. Those darker lines running up the photo are rivers.

Credit: MIT

These regular formations areas close as nature can get to the flow of teeth on a piano. Still, the formations are deceptively common. Satellite imaging has shown the same pattern again and again, under thick vegetation, or across cultivated fields. Its an odd phenomenon, and one of the few that Earth has in great abundance whilst Mars and the other planets do not.

This points towards a life-influenced terrain pattern,. Something unique to worlds that support life. Aside from the obvious implications of that, it means that on a virtual world that is trying to replicate the effect on formation of the landscape, life brings, such rolling hills are extremely desirable. If we can understand how these patterns are formed, we can replicate them, on worlds of our own creation.

Recently, an MIT geologist discovered the most likely mechanism for creating these features, and was able to model it in 3D, to realistic effect.

"Most landscapes are made up of ridges and valleys," says Taylor Perron, an assistant professor of geology in the Department of Earth, Atmospheric and Planetary Sciences. "The most fundamental question we can ask is 'What controls their size?'"

The basic mechanism that forms ridges and valleys, explains Perron, is a balance between two competing processes: gradual incision of valleys by flowing water, and the tendency of the land to slump into more rounded forms as soil slowly creeps downslope. The first tends to create sharp relief in the landscape, while the second process tends to smooth it out.

Whilst natural processes start the formation off, it is the work of burrowing animals over thousands of millenia which result in the smooth hill structures. Burrowing animals tend to burrow downhill, and over long periods of time, their burrows converge, all working away at the same areas; the gullies created by water run-off. This tends to smooth out the gulleys, creating soft, meandering valleys at regular intervals.

When replicating this in a VE of course you do not have to worry about the individual burrows, just that long curved trunks of land naturally form, and are slowly bisected by ruin-off valleys that smooth out over time. No sharp corners, no 'jagged cell grid', just smooth flowing hills, in what are often fairly straight lines.

References

How rolling terrain rolls: New study could help identify signs of life on other planets

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