Tutorials
Most of these involve Photoshop, but many of them work just fine in GIMP. Some of them aren't particularly helpful for Celestia; one of these days I'll get around to writing some of my own.
- Spoiler
- fyr02's Creating Realistic Gas Giant Textures
fyr02's other tutorials
trappistplanets' how to make realistic cloud textures
Fenerit's Making fictional 3D asteroids - images broken
Fenerit's Making fictional 3D planetary nebulae - images broken
Planetary Texturing Guide Repository - apparently I'm not the first to collect planet texturing tutorials in a forum thread! These have a KSP focus but a lot of the techniques carry over to Celestia
Nameless-Designer's Planet texture tutorial - use real coastlines to give your world an air of authenticity
An Advanced Guide to Planet Creation
Charred Planet Tutorial - skip some steps to get a texture instead
The Last Supernova Tutorial - how to build a star
Make Your Own Planet in Photoshop
Creating Seamless Spherical Textures - uses Carrara to fix the poles, but Polar Coordinates in Photoshop does the job too
GasGiant + Landplanet Tutorial - 2-for-1 special!
Tutorial - Making a Seamless Planet Texture
Fantasy Cartography Tutorial: Landscape Texture
Texturing and planet tutorial
Painting height maps for satellite-style maps
How To Make Gas Giant Textures for Kerbal Space Program Mods - but no one's stopping you from using them in Celestia...
Gas Planet Tutorial - you've probably seen this one
green planet tutorial - this one's for the GIMP crowd
GIMP Earthlike Planet Texture
Planet city light map tutorial - more GIMP
surface tutorial - part 01 - turning a stone texture into a terrestrial world
surface tutorial - part 02
surface tutorial - part 03
surface tutorial - part 04
3DS Max Planet Map Tutorial - making planet textures for 3DS Max in Photoshop
3DS Max Gas Giant Tutorial - combining the textures in Max to create a gas giant
3DS Max Planet Tutorial - combining the maps in Max to create a terrestrial planet
3DS Max Planet Rings Tutorial - planetary rings for Max, ignore everything after step 1 for Celestia
3DS Max Planets - The End - some interesting ideas, not particularly helpful for Celestia
Making a Dwarf Planet - remixing lunar DEMs into new worlds
Resources
- Spoiler
- john71's HD Texture Link Collection
trappistplanets' Height Map from Mesh in Blender - convert asteroid shape models into DEMs!
MrSpace43's Simple Blender Cloud texture Maker - pretty self-explanatory, bakes procedural noise into cloud maps
Astra's Raw Textures - 5 GB of ice, rust, and texture brushes
Blend Swap | Tectonic Planet - a Blender noise setup I made a while back, generates reasonably realistic terrain for terrestrial planets
JPL Photojournal - NASA's image access home page
NASA Earth Observatory - images from our homeworld
EOSDIS Worldview - interactive data viewer, allows snapshots up to 8200px2
USGS Astrogeology - maps of other worlds including DEMs and global mosaics
MRO Image Gallery - basically Earth Observatory, but for Mars
terrain.party - designed to grab heightmaps for Cities: Skylines but you can use them for anything
planet1 - generate procedural worlds in your browser!
SDO archive - high-res images of the Sun in various wavelengths, from SDO
Blue Marble Next Generation - 12 monthly maps of Earth from 2005, plus bathymetry, clouds, terrain shading, and SRTM elevation maps
Natural Earth III - dataset based on BMNG, in a different style with more cloud options and bump/spec/night maps
GOES-East - Latest Full Disk Images - real-time weather satellite imagery, might be useful for cloud maps. see also GOES-West
Unsplash - the internet's source of freely usable images
Pixabay similar to above
Pexels another free stock site, plenty of overlap with Unsplash and Pixabay as their images tend to get reposted
Picdrome Collection of CC0 photos, I've linked to the textures section. Apparently down, changed the link to point at the Wayback Machine's copy. No guarantees on how much it saved.
Wild Textures - free high-res textures
Public Domain Texture Sites - Google spreadsheet of various texture sites, some overlap with this one
TexturesForFree.com - more free textures
Paul Bourke's texture library - most of these are old and low-res, you might still find them useful somehow
WebGL Fluid Simulation - high-res fluid sim with built-in screenshot function, may be useful for gas giant textures
Vervette - fluid painter, may be even more useful for gas giant textures
Artbreeder - generate (low-res) images with the power of AI! they have a "sci-bio" art generator that can create an endless variety of abstract textures from nebulae and terrain to alien cityscapes and semi-organic materials
Gas Giant Resource Pack - free gas giant textures
Gas Giant Resource Pack 2 - the sequel
Gas Giant resource pack - not to be confused with the first one
Gas Giant Storm Brush Pack
Gas Giant Storm Brushes 2
Nebula Brush Set 01
