drawing an interstellar nebula

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yellowmoss
Posts: 3
Joined: Fri Jun 17, 2011 11:30 pm

drawing an interstellar nebula

Postby yellowmoss » Fri Jun 17, 2011 11:57 pm

All,

I'm trying to draw something that looks like an interstellar nebula within the confines of an irregular, closed shape. I drew the irregular closed shape, then selected filters->ABCs->noise transparency. It looks plausible inside the shape, but it cuts off sharply at the edges. I could do a simple fade-out filter at the edges, but this would still give an impression of a well-defined shape, whereas what I want is a less-defined "cloud-like" fade-out. What is the best way to achieve this effect?

Thanks in advance
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llogg
Posts: 443
Joined: Tue Mar 11, 2008 7:30 am

Re: drawing an interstellar nebula

Postby llogg » Sat Jun 18, 2011 9:52 am

You can create a pattern of your noise transparency, fill your irregular shape with the pattern, then blur the whole thing. Not sure if the interior blur matters that much to you. If it does I can give you a couple of ideas for work arounds.
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brynn
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Re: drawing an interstellar nebula

Postby brynn » Sun Jun 19, 2011 11:47 am

What about using a mask? Or radial gradient plus blur? Or all?
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yellowmoss
Posts: 3
Joined: Fri Jun 17, 2011 11:30 pm

Re: drawing an interstellar nebula

Postby yellowmoss » Tue Jun 21, 2011 11:50 pm

I found that I can:

  • edit the "noise transparency" filter
  • edit turbulence effect parameters
  • change the type from "fractal noise" to "turbulence"
Whereas "fractal noise" gave me non-discrete cloudiness, "turbulence" gives me discrete-looking cloud shapes. Theoretically I should be able to manually find the edges of interesting-looking clouds and remove everything else. I'll be fiddling around with this and hopefully posting a few examples.
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yellowmoss
Posts: 3
Joined: Fri Jun 17, 2011 11:30 pm

Re: drawing an interstellar nebula

Postby yellowmoss » Wed Jun 22, 2011 11:54 am

So here are the complete steps I used:

  • create a large-ish square
  • set fill to linear gradient
  • apply the "noise transparency" filter
  • edit the "noise transparency" filter
  • edit turbulence effect parameters
  • change the type from "fractal noise" to "turbulence"
  • fiddle with the turbulence parameters until I find an "interesting" cloud of appropriate size
  • create a shape of appropriate size to cover the cloud I want to keep
  • position the shape over the cloud (set to 5% transparency, black fill to help position the shape to completely cover the cloud)
  • select the square I created in the first step, and the shape that is covering the cloud, then clip

I did this with six different shapes/colors, and am attaching the saved file.

Comments/suggestions are of course welcome.
Attachments
nebulae.svg
Nebulae
(29.67 KiB) Downloaded 425 times
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brynn
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Re: drawing an interstellar nebula

Postby brynn » Wed Jun 22, 2011 12:27 pm

Oh nice!
I had a different idea of what you were describing. Those look nice :D
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