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View Full Version : What's a good cloud renderer for GIMP?



HBrown
10-04-2012, 02:02 PM
I'm dissatisfied with the cloud renderer in GIMP. The local texture is nice but the clouds tend to line up along the diagonals, often egregiously so. The best I can do is try multiple seeds until I find one where these artifacts are minimized (but not eliminated).

I rummaged around on the GIMP plugin registry but did not find any replacement cloud renderers.

Does anyone know of a better plugin/script/secret incantation that I can use to get good clouds?

Thanks,
Hugh

RobA
10-04-2012, 09:59 PM
I use the felimage plugin http://fimg-gmplugins.sourceforge.net/

-RobA>

HBrown
10-05-2012, 01:03 PM
Thanks Rob. I have felimage, but I'm looking for something a little different.

I like the texture of GIMP's solid noise, but not the regular spacing of the curds.

Here's an image that I hope will illustrate what I'm looking for:
48824

The left half is GIMP's solid noise, and the right is done with felimage noise. For the felimage side, I twiddled with the settings until I got about as close a match as I could get to the GIMP side. I like that the curds don't line up, but the gradient from dark to light is much smoother than with the solid noise.

Inset on the felimage side is close to what I want. It's built with several iterations of the felimage filter stacked up, with assorted adjustments to scale each layer's range and density. If I experiment a bit more, I think I can get what I want, but it's slow, as in S L O O W. As a manual process, it took about forty minutes to build this example. I'm working on a script to do this, but it will still be slow, requiring five or six separate invocations of the felimage filter.

I was just hoping some clever person out there had come up with a more efficient solution.

Thanks again,
Hugh

RobA
10-06-2012, 01:36 PM
Just change the settings. Here is a single run with felimage that looks similar to your desired result:
48861

The settings I think I changed from defaults are:

Basics
Width and height: 20
Lattice Noise
Ordinary fBm
Octaves: 15
Lucanarity: 2.0
Hurst Exponent: 2

Output
Gain: 0.2

More adjustments of Gain and Bias should get even closer to your higher contrast result.

-Rob A>

HBrown
10-08-2012, 09:50 PM
Thanks, Rob! I guess I just didn't fiddle with it enough.

--Hugh

RobA
10-08-2012, 10:23 PM
Thanks, Rob! I guess I just didn't fiddle with it enough.

The real trick is to fiddle enough to figure out what the heck all the options actually do!

-RobA>

jbgibson
10-09-2012, 09:29 PM
A simple, if tedious solution might be a decent resolution digital camera, and a sky to point it at. Some days even the natural chaos above me has artifacts (contrails... ) but when we had the "map based on real clouds" contest I continued snapping pix of different kinds of clouds. "Buttermilk sky" approximates the generated clouds y'all are discussing.

DrunkenEwok
10-26-2012, 10:16 AM
The real trick is to fiddle enough to figure out what the heck all the options actually do!

-RobA>Out of curiosity, since you seem to have figured out most of the fiddly bits, any chance you can share some of that expertise in a tutorial? Pretty please? :D I've been fiddling with noise generators for years (not to mention reading manuals) and I'm still not 100% certain what sort of results I'll get...

Also - in case felimage isn't sufficient, MathMap also has some pretty good noise generators.