I just completed a piece with Tor.com, for a short story entitled, "Sanctuary," and there’s a part in the story of a character that actually does a sketch of two generation ships in low orbit over an Earth-like planet. A small deltoid ship leaving the hangar deck.
I did a few too many thumbnails trying to decide just how I wanted to see these ships. But clients love it when you do that. You just have be careful to show them the only ones you truly want to illustrate. (I've messed that part up many times while trying to please the client, and neglecting my own tastes. Which is why they usually come to you in the first place.)
The character was probably onboard when they drew this scene, but I preferred to use a pov from outside the ships as I wanted to see more ship design. Maybe they were using an extra-vehicular device, much like NASA has developed. I read into it a bit in order to get a good drawing out of the assignment.
The visual was described rather specifically in the story so I needed to make it look like a sketch. We kept it loose to reflect that the character was probably scratching it out in a short period of time. Conveniently, the sketch, completed in soft pencil, then became the final piece for the story.
I also figured the character was a pretty fair drawer.