Copyright and influence: drawing a sculpture

In this thread discussing copyright, slipster says,

Today, I was wandering through the Art Gallery of Ontario. There was an open house relating to the new building being designed by Frank Gehry, but the entire gallery was open.

I wandered into a gallery containing the abstract sculptures of Henry Moore, where I had an idea for a drawing.

I am aware that I may need permission from the gallery to draw, take photographs, etc, for non-copyright reasons. They might need to arrange working space that did not disrupt the flow of people through the gallery, or they might want to make sure that my taking pictures did not damage the paintings, for example.

My question: do I need copyright permission to draw the sculptures and use the drawings in my own work? The drawings would serve as a base for more elaborate work.

I don’t want to sell a drawing of Moore’s The Archer, for instance, but what would happen if I drew a picture of City Hall that included that sculpture sitting out front, as it does in real life? What would happen if I took a photograph of the sun ‘rising’ over the curved surface of the sculpture as I moved out of its shadow, and went to sell that? Do I have to ask McDonald’s for permission if I want to publish a cartoon of a streetscape that includes a McDonald’s sign? Does it matter if the real streetscape includes the sign?

This FAQ on derivative works seems to indicate that some of these cases might require permission, but it’s still unclear to me… especially the streetscape question.

Does anyone know more about the case that slipster mentioned in passing?

I think that something on public display is fair game. For instance, if you were to take a picture of City Hall with a beautiful cloud formation behind it you could sell that. I think that the main thing is whether or not it is a major part of the production. If your photo or drawing is little more than a replication of the statue you would probably be in trouble, but if you were to be drawing the entire City Hall you would pretty much be required to include the statue.