I am going to Vancouver soon to shoot some establishing shots in the mountains for a feature film. Then after I am going to shoot the rest of the movie in Saskatchewan or Alberta, most likely. I will add set extensions to match the locations. However, how do you know if set extensions will match? Do filmmakers look at several set extensions, then go out scouting locations that will match those extensions, or is it better to do it the other way around and shoot first, then match?