Captain America, Lord of The Rings and The Social Network have each used a technique where an actor has either been shrunk down (Captain America & LoTR) or completely replaced by a face (Captain again & Social Network).
My question is what kind of planning and production goes into pulling off this kind of feat? I am wondering about the specific technologies are used for what seems to be either camera tricks or CGI, using these movies as examples.
Is it pure CGI on all levels? Is it all camera tricks with minor CGI? Or is it a nice synergy between the two?