How I make planetary textures - a short tutorial

[Wallstone]

After reading quite a few posts here, I learned quite a bit. Thank all of you for your creative suggestions, and thanks also to the authors of Celestia. As my way of giving back to the community, I decided to write a short tutorial about how I make earth-like planets, out in the barren cosmos. I welcome any suggestions.you might have (especially for how to improve cloud patterns), and will try to answer any questions I get hit with.

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I'm no artist, but I do need good artwork for space-based books, album covers, etc. Since the program knows about extrasolar systems, I can pick one of those, choose a planet, modify the exrtrasolar.ssc file to my specs (using Earth or other data), and then add the textures to the highres directory.

My graphics card can only handle 2k textures. That's good enough for me right now, though later I will probably delve into Virtual Textures (and upgrade the graphics card). I use two programs to create textures:

* PlanetGen V. 4 Beta 4, to create the planet info
* GIMP 2.2 (with DDS and NormalMap add-ons), to edit then into final form.

(Below, I save two of the texture files as a DDS, but you can save them as JPGs instead, although Celestia can't load them as fast - If your card can handle DDS, do it!)

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PlanetGen has a number of settings - read the docs, and play with the settings. It creates two kinds of textures: a relief map, and a climate map. After you get those two files created, do:

To edit the main Celestia background image:

1. Bring up Relief Map
2. Use Filters -> Map -> Bumpmap - set to taste (it's a good idea to read the Docs...)
3. Open as Layer Climate Map
4. Use Layer - Transparency - > Color To Alpha, set black (000000) as the color
5. Use Image -> Merge Visible Layers
6. Save As a DDS file to High-Res directory (or wherever applies) - I use DXT1

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To make the Celestia night-time pic (there's no doubt better ways to do it, but this is a quick and dirty solve):

1. Open Relief map
2. Use Filters -> Decompose (RGB, Decompose to layers, which is the default)
3. The Blue layer should be on top, so you can invert that with:
* Layers -> Colors -> Invert
4. To get a night-time appearance, I simply adjust the brightness/contrast to something that looks decent:
* Layers - Colors - Brightness-Contrast
* I set the brightness to -127, and play with the contrast to get something semi-decent
* This is usually brightness at -127, and contrast at +127
5. Use Image -> Merge visible Layers
6. Save As a DDS file to High-Res directory (or wherever applies)

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If you want white clouds, those are fairly simple. If you want white, purple, blue, and green clouds, it's a bit more complicated (I haven't tried those layers yet, so don't ask me to explain it just now...)

How I do it...

1. Open a blank file (I use 2048x1024)
2. Use Filters -> Render -> Clouds -> Solid Noise
3. You can optionally click on Turbulent
4. You'll want to make sure that you click on tilable, because the patterns need to go from edge to edge
5. Change X and Y to your liking, and keep clicking New Seed until you see what you want (play with it until you're happy with the preview)
6. You will usually want a Detail higher than 1....
7 Click OK when you like what you see - this will generate the clouds pattern
* (If you're gonna change the cloud color, now's the time)
8. Use Layer - Transparency - > Color To Alpha, set black (000000) as the color (unless you changed the white clouds to something else - don't know the specifics in this case)
9. Save the new checkerboarded file as a PNG file, as JPGs can't have transparencies, and DDS files (on this system anyway) suck with transparencies

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Later on, I'll post some of my planets via link to this thread. I just don't have them online yet, but that will change over the coming weeks. They're far from perfect, but not bad coming from a non-artist, at least in my opinion. I'm sure somebody else can improve this tutorial (hint, hint)....

- Danny

[BobHegwood]

Well I'm certain that your contribution here oughtta be useful to
plenty of people who don't live in Celestia, so thanks for making the
effort.

Always nice to see people making contributions to help each other.

Good stuff, and thanks.

Take care, Brain-Dead

[Wallstone]

Well I'm certain that your contribution here oughtta be useful to
plenty of people who don't live in Celestia

I don't live in Celestia, but there's this village called "Continuum" that's pretty cool. That's Continuum as in the old game Subspace, not the Q Continuum, from Star Trek. Wasted away many hours in that game....

Back to topic - is there any way to have multiple layers of clouds in Celestia? As in multiple heights? That would be a cool feature....

- Dan

[cartrite]

I once tried to have a couple of layers, I did it by defining a couple more earths with no texture and assigned them each a different cloudmap. I suppose if you played with it.............
http://www.celestiaproject.net/forum/viewtopic ... 9470#79470
http://www.celestiaproject.net/forum/viewtopic ... 9779#79779

I am currently looking into hdf files and how to extract point cloud data from them. The information is there, I just don't know what to do with it yet. I may be able to create a cloud normalmap from them but I'm also looking into how Lidar point cloud .las or xyz point cloud files are created and how they may be used with Celestia.
cartrite

[Fenerit]

In order to mantain transparent also the material for having the right mouse option without write the same altmap's .ssc declarations for each sphere , see this tutorial:

http://forum.celestialmatters.org/viewtopic.php?t=37

[Fenerit]

I've found this tutorial for procedural methods in making planets:

http://www.foundation3d.com/index.php?c ... ticleid=31