already been done....

have u watched Superman Returns...?
they used a digital double of superman in a close-up view....
if you look carefully, in some scene the actor looks like doll haha....
that because, its CG.....

before this, many digital double had been used in a holywood movie,
but most of them are from a far view....

maybe in a couple of years, we can see a lot of digital double
that doesnt look too doll-ish or CG-ish... lol...

.