Re: Avengers: Age of Ultron Set Photos (high quality) Set pics
Knowing a little bit about CGI works, its pretty obvious that the stand in is simply there for lighting purposes. The stand in itself not actually going to be in the movie. The design however will. And what is up for debate is what character the stand in is for.
If Ultron was in the scene, he'd be in a mocap suit as well. So Ultron could very well be one of the mocapped guys running around. But if that stand in was for Ultron, why would they not have a lighting reference the goons, unless they look exactly the same as him? See where I'm going with this?
Right now, nothing points to it being Ultron, other than the fact that he's metallic.