Hrm, well, first of all maybe I should begin with a disclaimer ;-)   All this talk about copyright is just informal wonderings not to be taken as legal advice.

I think there's something about historical subjects that might be ok. Recreating the USS Constitution, CSS Merimac, USS Monitor, HMS Victory, etc. Have the merchants in Renderosity selling these models cleared away with these historical things? This might be something TheBryster might be interested in if he wants to sell his train model once it gets finished.

Not sure, but it would be odd to make a Bryce Canyon scene and have to ask permission with the US Park Service to sell the render.

I wonder if the case of a story is enough to put a foot note, like a disclaimer, like many documentaries or docu-dramas have stating the characters and events are purely fictional.

In New Orleans there's a bunch of artists that get to Jackson Square in the French Quarter and on Saturday/Sundays are doing paintings of scenes around the city and selling them. By the looks of them, I doubt they have any license. Looks are deceiving, but wow. Anyway, they just come and set up their painting boards and sell for like $30 to $250. Anything from local businesses, swamps, river boats, streetcars, and the city skyline. I'm sure now they are also painting Katrina events.