More noise experiments

[ravells]

The depth of your knowledge never ceases to astound me, Waldronate. I just assumed it was contental sized but the more I even look at them in google earth the less 'natural' they look. Some of them are just downright bizarre.

[Karro]

The depth of your knowledge never ceases to astound me, Waldronate. I just assumed it was contental sized but the more I even look at them in google earth the less 'natural' they look. Some of them are just downright bizarre.

I, for one, assumed a very close regional scale, say between 50 and 200 miles across.

[Karro]

That sort of moth-eaten coast is what I would expect of a sediment-starved coastal marsh that's actively subsiding (e.g. the coast of Louisiana). ...

So... I just had a look at Lousiana in Googlemaps. Man, that is CRAZY looking. How does the Mississippi not dump into the ocean sooner, but continue down a long, thin, couple-mile-wide stretch of sediment poking out into the Gulf?

[waldronate]

The Mississippi still follows its path to the Gulf because of human intervention. It is really little more these days than a concrete-lined barge canal critical to the US economy. The old river control structure where the Atchafalaya and Mississippi diverge has a federally-mandated water split between the two rivers. If it were up to the river, it would have gone down the Atchafalaya some time ago, leaving New Orleans and its huge port as a silting backwater on the river.

The scary thing about the Mississippi delta and Lousiana coast is that it's not growing because the mouth of the river dumps over the edge of the continental shelf, putting most of that silt load into the deep ocean. Ocean eats at the coastline, deep sediments compact, and the land sinks. No new sediments replace the lost land.

Rivers silt up. Rivers change course. It's what they do. The classical city of Troy had a harbor; The site of Troy today is Troy is fully 5 km from the coast. Ostia, the port city of ancient Rome, is 3 km from the coast. To expect that our cities should be immune from this is silly. If you want to live on the coast you need to make concessions. If your city is wiped out by a hurricane, you either build a new one in the same place and same conditions and accept that it will happen again (New Orleans) or you raise the whole city site and armor the heck out of it (Galveston, TX). Even then, you know you're going to lose eventually. If we just keep building higher levees around cities like New Orleans then eventually it will a little sucker-mark of dry land bounded by hundred-foot-high barriers out in the middle of the Gulf.

[Gandwarf]

Even then, you know you're going to lose eventually. If we just keep building higher levees around cities like New Orleans then eventually it will a little sucker-mark of dry land bounded by hundred-foot-high barriers out in the middle of the Gulf.

More than 25% of the Netherlands lies below sea level and 60% of our population lives there. We keep building higher dikes and reclaiming land. We are bound to lose this struggle. It's now IF, but WHEN. We are very good at stalling for time though
Who knows, maybe it will get colder and more water will start to freeze up again... LOL.

[waldronate]

"Father: Listen, lad. I built this kingdom up from nothing. When I started here, all there was was swamp. Other kings said I was daft to build a castle on a swamp, but I built it all the same, just to show 'em. It sank into the swamp. So, I built a second one. That sank into the swamp. So, I built a third one. That burned down, fell over, then sank into the swamp, but the fourth one... stayed up! And that's what you're gonna get, lad: the strongest castle in these islands."

Yes, I'm familiar with your kind...

[Steel General]

Love me some Monty Python!

[RobA]

Great discussion my little experiment generated. What I was really trying to do was to have variations in the coastal shape.

Most of the noise function generators produce such a uniform noise that in the desired scale (50-200 miles is a reasonable guess of my intentions, Karro!) it looks weird. Most places in the world I have looked at have stretches that are smooth, then stretches that have a higher fractal dimension (did I get the lingo right?)

The other thing was to try an introduce some features that are uniform x/y, hence the attempt to stretch the noise pattern then rotate it and blend that in.

Because I used masks that were a feathered coast extension, it let the islands "bleed out" often in a weird and undesirable way ...

ok 10 seconds to blow away the smaller offshore islands, improvement?


-Rob A>