Do you mean the wide shots of the gunship moving through Coruscant, or the close-ups of Koe and Qoz aboard the gunship?
In the case of the former, I just put the gunship on the end of my desk, took a few angles, and then cut them out in photo shop. I copied and pasted the cutout gunship onto various coruscant backgrounds, and then scaled the gunship layer until it looked like the scale was proper.
Next I attempted to balance the levels and color balance for either the gunship or the background (whichever looked less natural). When I got those looking relatively consistent, I blurred the background to account for motion or distance. I added the fog effect (see above) when necessary, and erased as needed.
Hope that answers your question, and thanks!