This illustration was done for Hero Games for their book "Star Hero". The station was modeled in Google SketchUp. I exported the model as a 2D image with nothing but lines, then with nothing but shading, then with nothing but shadows, and composited them in Photoshop, along with a whole bunch of special effects. The planet was pure photoshop, using some distort and liquify filters, as well as a photo of some ground texture.
Frankly I've been fascinated by the explosion of free and open source software (SketchUp is free, Blender is free and open source). I haven't tried Gimp, but since Photoshop is still pretty much the standard, I'll probably stick with that for a while.
