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Cloud Distribution

Started by laeuchli Jul 18, 2008 at 4:55 PM 7 replies 2.1k views

Original Post

Jul 18, 2008 at 4:55 PM

Dear All, Does anyone have a good fractal method for generating cloud distributions? I'm currently using just a simple fBm fractal based on perlin noise. This looks ok, but the distribution is too regular. Does anyone know a better method? Texturing and Modeling has lots of information on generating 3D structures for a single cloud, but not much on large 2D cloud maps, or even good methods of distrubuting the 3D clouds. Thanks for any suggestinos. Jesse

alfith

Jul 19, 2008 at 6:27 AM

To distribute "objects" I usually do something like this:

1: randomize a position
2: randomize an angle
3: randomize a lenght (high probability of getting a small lenght, low probability of getting a large lenght
4: move from previous position to new position and add an "object" there
5: goto #2 a fixed number of time

Pragma

Jul 19, 2008 at 9:16 AM

Try this, the author suggests using a threshold plus a simple exponential sharpening. It's tunable and the results look pretty good.

laeuchli

Jul 19, 2008 at 12:07 PM

Quote:
Original post by Pragma
Try this, the author suggests using a threshold plus a simple exponential sharpening. It's tunable and the results look pretty good.

I've tried that, but the resultant structure is pretty local.

Pragma

Jul 19, 2008 at 8:08 PM

Did you try just adding more lower octaves of noise?

laeuchli

Jul 20, 2008 at 1:05 AM

Yes, that adds more fine detail the clouds, but doesn't much change the overall structure.

Krokhin

Jul 20, 2008 at 1:39 AM

Quote:
Original post by laeuchli
Yes, that adds more fine detail the clouds, but doesn't much change the overall structure.

What do you mean,saying "too regular"?
To understand it,you must look at real sky or fotos,from ground or space.
Day time clouds,classic Benard(thermic) cells

[Edited by - Krokhin on July 20, 2008 4:39:27 AM]

Matt Aufderheide

Jul 20, 2008 at 8:55 AM

Quote:
Original post by laeuchli
Yes, that adds more fine detail the clouds, but doesn't much change the overall structure.

I think he meant lower scale octaves, not higher..that mean more low frequency noise. Also, try giving different wieghts to the lower frequency noise when blending the octaves. There are many ways of blending the octaves.
You can also try messing with the actual noise textures, instead of just usingthe classic noise..try using a two pass type thing where you misx regular noise with blobs or something.

Pragma

Jul 20, 2008 at 6:10 PM

Quote:
Original post by Matt Aufderheide
I think he meant lower scale octaves, not higher..that mean more low frequency noise.

Yes, that's what I meant.

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