It is currently Fri Mar 29, 2024 4:49 am


All times are UTC - 5 hours [ DST ]



Post new topic Reply to topic  [ 3 posts ] 
Author Message
 Post subject: Making an asteroid field
PostPosted: Sat Aug 20, 2016 1:55 pm  (#1) 
Offline
GimpChat Member

Joined: Jul 17, 2016
Posts: 293
Location: Arlington, TX
I had so much fun with this technique I had to share it.

  1. As with so much of what I do, this trick starts with a noise layer. The settings really depend on what you want to accomplish. Larger X/Y sizes will result in more small asteroids, smaller X/Y will give fewer, larger asteroids. Also, higher detail will result in rougher asteroids versus lower detail giving smoother asteroids. If you're only after one or two really big asteroids I don't know if this technique will be suitable.

    This is the initial noise. I used fairly low X/Y, around 4 or so.

    Image

    For comparison, I'm actually going to do two images at the same time. You'll be able to see how minor tweaks to the settings can change the final result. One side will have "smooth" asteroids from setting the detail at 1 and the other will have rocky asteroids from a 15 detail.

  2. Run Colors>Threshold on your noise layer. Now you can see how the detail setting makes a difference.

    Image

    Both sides have the same seed and X/Y settings. So they started as the same overall pattern. But the difference in the detail makes a huge difference in the smoothness of the border. Play with the threshold til you get the look you're after. Or even go back and redo the noise with new settings. As always, it's your picture, you make the calls. Once you are happy with the overall look of the field, run Gaussian Blur on the layer. I used a blur of 30 on this example. I think I probably should have gone higher. This is one of those time when the only way to figure it out is to experiment. Set this layer on "Multiply".

  3. Create a new below the layer and fill it with turbulent noise. For this tutorial, I maxed out all the settings. But each piece is different. This is the layer that will create the larger bumps and craters on our asteroids. Set this layer to "Multiply" also.

    Image

  4. Create yet another layer below the previous one. Fill it with Filters>Render>Clouds>Plasma. Here you probably also want max turbulence. Desaturate the plasma when it is finished. This is going to give us our finer surface texture. Leave this layer on "Normal".

    Image

    Right now, your layer stack should look like this;

    Image

    The Plasma layer is "normal", the Noise layer is "multiply", and the Min/Max detail layers are both "multiply". Notice that I copied the min/max layers. I prefer to copy layers before doing destructive things like blurring. So if it didn't turn out right I could always try again.

    And this is what the image looks like with that combination;

    Image

  5. Now we need to take those shapes and give them texture. This is where the magic happens. First, right-click the layers dialog and select "new from visible". This gives you a new layer to tweak without destroying your other layers like merging them would. So if the look doesn't turn out right you simply delete the bumped layer and do "new from visible" again to start over. Then Filters>Distorts>Emboss on this new "Visible" layer. Here are the settings I used for the max detail (rough) asteroids;

    Image

    Of course, you may need different settings. The "emboss" option may also work better in your case, or "lighting effects", or Filters>Map>Bump map. Whatever you use, make sure to use the "Visible" layer as its own map. Also, this is where the blur we did on the initial layer becomes important. A larger blur gives a "rounder" appearance to the shape here. But it also loses some of the profile contour.

    I was unhappy with the way the texture looked on the Min detail asteroids. So I duplicated and blurred the Noise and Plasma layers. The blurry layers produced a smoother texture that works better with the smoother profile of the Min detail asteroids. So now I have a layer stack that looks like this;

    Image

    The Min/Max Field layers in that screenshot are the "Visible" layers created in the previous step. Yes, it does get confusing at times keeping all the layers sorted. Using the right names makes all the difference.

  6. I'm going to be a tease and hold out on showing the final result for just a little longer. First, we need to add some color. I suppose it would be fine to leave them grayscale. Or maybe just add some HSV or RGB noise. There's probably no "wrong" way to go about it. But I'll show you what I did.

    I created a new layer above the asteroids, filled it with a pattern, blurred it, and set the mode to "Color".

    Image

    That's right, I have leopard-print asteroids. :yes But with the blur and the "Color" layer mode you will never notice. It's just one way of getting those slight variations in color that are critical any time you want any degree of realism.

  7. Now go to your original layer, the one you did "threshold" on. "Select all" and "copy". Then paste this selection as a layer mask on the final layer and the color layer. This is the easy way to cleanly get rid of all that pesky black surrounding your fancy new asteroids. Add a starfield, or whatever, under the asteroids and you have a snazzy space scene. Or asteroids in your living room. Whichever. It's your picture, do what makes you giggle.

Here's mine.

Image

Notice that while my asteroids have nice profiles they appear to be kind of "flat". It's almost like they are slices of something rather than round objects. I'm hoping somebody who understands depth maps better than I do can provide some insight into how to fix that.

Also, it is easy to go back over the asteroids with a big, soft brush set to "burn" mode and low opacity to knock down the highlights and deepen the shadows. Which does help some with the "flat" look.

_________________
Just a short while ago I was a complete idiot when it comes to GIMP. Today, after many hours of practice, reading, and watching tutorials, I am proud to say I am an incomplete idiot.

Image


Share on Facebook Share on Twitter Share on Orkut Share on Digg Share on MySpace Share on Delicious Share on Technorati
Top
 Post subject: Re: Making an asteroid field
PostPosted: Sat Aug 20, 2016 9:13 pm  (#2) 
Offline
Global Moderator
User avatar

Joined: Nov 16, 2011
Posts: 5128
Location: Metro Vancouver, BC
Sasquatch, you've been busy, 3 tuts in 4 days. :bigthup

_________________
Image
Gimp 2.8.18, Linux, median user
Gimp Chat Tutorials Index
Spirit Bear (Kermode)


Top
 Post subject: Re: Making an asteroid field
PostPosted: Sat Aug 20, 2016 9:31 pm  (#3) 
Offline
GimpChat Member

Joined: Jul 17, 2016
Posts: 293
Location: Arlington, TX
I hope I haven't exceeded my quota. :)
Started using the pointers you gave me. Also started saving the images so I can possibly convert these to pdf if needed.

Out of tut ideas for now. Back to work on regular projects.

_________________
Just a short while ago I was a complete idiot when it comes to GIMP. Today, after many hours of practice, reading, and watching tutorials, I am proud to say I am an incomplete idiot.

Image


Top
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 5 hours [ DST ]


   Similar Topics   Replies 
No new posts Attachment(s) Making Art from Script

4

No new posts I am making GEGL filters and need help

1

No new posts Making A G'MIC 3D Elevation Animation

3

No new posts Attachment(s) Quality loss while making GIF

17

No new posts Attachment(s) Help making selection between two arbitrary lines

12



* Login  



Powered by phpBB3 © phpBB Group