Well nearly all shots like this one will be touched up with computer enhanced graphics.

I don`t think you`re meant to see the grounds...the tents are a while away from there - remember thousands of wizards are supposed to attend so it wouldn`t be realistic to see the stadium in the background.

Though we've seen bird's eye view shots of it, I don`t think we'll see the finished product until the film comes out, it'll be something WB will want to keep as secret as possible.