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Thread: More noise experiments

  1. #1
      RobA is offline
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    Post More noise experiments

    I've been working on getting a more natural looking coast from the noise functions in a raster program. Here is such an effort:

    More noise experiments-test.png

    It is a combination of a number of gimps standard noise functions and felimage noise at different levels, masked off by coast proximity and large turbulent noise, plus one noise layer motion blurred then masked as well. These are all thresholded and combined by various multiply and screen modes.

    Thoughts on the "naturalness" of this?

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      Karro is offline
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    It looks pretty natural except for one thing that I'm not completely certain about: how common are those coastal lakes in real life? Here you see a large number of lakes disconnected from the ocean but very near the coast, and very few inland. Is that normal, IRL?
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      Jykke is offline
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    I was thinking about the same thing as Karro.

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    Don't know how natural they are, but you get similar results in Photoshop if you fill a layer with B&W clouds then hit it with Threshold.

    I usually end up having to zoom in and delete/fill in various small lakes and islands.
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      Redrobes is offline
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    I'm with Karro and Jykke, my rather amateurish experience has been that these lakes are either above or below sea level and that water would either rush in or out and open up a channel to the sea which then widens through tidal action. I have been quite skeptical that through noise alone can you model the coast line. As a first pass its fine but I think you either need to work on it with some gray matter guesswork or some math simulation of water flow from rivers or the sea. It would be interesting to see some satellite photos of some areas that have pics from about the 1970's through to present and to see an animation of them showing how its changing. Although I doubt that the movement would be all that much it might be just enough to see the underlying trends and model them.

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      Karro is offline
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    Hmm. Did some quick zooming in on Googlemaps, just to get a sense (looked at the eastern coast of U.S. and coast of France/Italy as examples). Looks like large numbers of coastal lakes aren't that uncommon. What I can't say is whether they are more or less common than inland lakes (that's harder to gauge, I think). On the other hand, what's also hard to gauge is whether what I see in Googlmaps are really just lagoons and bays and whatnot that are very highly sheltered.
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      Aidan is offline
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    I'm minded of lochs in Scotland, but from what I understand those are rather long and thin.

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      ravells is offline
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    Nearly there...maybe it's a young planet? As the others said - the landmass fractures too gradually towards the coast so you end up with lots of isthmuses and coastal lakes. Otherwise it looks fab.

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      Jykke is offline
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    Actually if you manually just fill some of the coastal lakes, the end result is quite nice So the lake thing probably isn't a big issue. Would be interesting to see all the steps needed to produce this.

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      waldronate is offline
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    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). The large areas of uniformly tiny islands at a uniform distance from the coast are more disturbing to me (I am familiar with barrier islands, but they tend to have a different proportion and distance distribution). It's a good first-glance plausible result, but I'm not sure how much I can really say about its "naturalness" without a scale and other details such as water flows. Overall a good multi-fractal synthesis technique.

    The big thing about this coastline is that it's easy enough to rationalize the "naturalness" of parts of it in many ways. However, each section of the coastline seems to be at a different scale and type than others. Hard-rock coasts like Canada or Norway have a different character than soft sediment coasts like the US Gulf Coast or Bangladesh. A view from 5 miles up is quite different in character than one from 100 miles up, no matter where you are. I often see maps here where one set of features don't match another (for example, a fractal forgery that works for a 500 mile stretch of coast that's then modified by a fluvial model that's appropriate for a 1 mile stretch of coast). Most people won't notice it, but I've made too many bad coastlines over the years and have an unfortunately large library of incongruities available for comparison. My sins on the FT terrain synthesis and river finding still haunt me...

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