I need to make this post to give you some precisions.
The custom surface maps will have three resolutions: 1024 * 512, 2048 * 1024 and 4096 * 2048.
From the alpha 6 the 1024 ones will be included in the full and assets-only packages. When I will finally put back an installer for the 1.0 version, they will be also included by default in it.
I consider the 2048 and 4096 ones as optional, and they will be available in separate downloadable packages.
I do that because, as you certainly seen already, the 3D in FARC is pretty basic and has only a function of illustration in the background, the game in this way isn't a real 3d game. So to put by default high resolution textures seem to be a waste of bandwidth and time for you. But on the other side I want to let you the choice to use them or not, so that's it. Theses maps affect the render in the 3d but also into the surface panel, where the surface of the currently selected orbital object is displayed.
So that's it. I actually put in the main design document the complete procedure of the data linking for Fractal Terrains and also the procedure to render the maps. It's a bit of work but it will make it far easier in the future when I will have to render many surface maps for many planetary systems.
PS: I will make a special package to deliver the maps to OpenGameArt.org, and contribute to this community, after the release of the alpha 6.