This sequence of images from the Hobbit reveals something you may have never thought about before, the isolation an actor can suffer when filming a movie with a lot of CGI. In this production shot, actor Sir Ian McKellen who plays Gandalf breaks down after the torment of having nothing but green screens and sticks to talk too.
The reasons that these films are mostly shot in CGI can vary, but for The Hobbit, it was because they filmed it in stereoscopic 3D, therefore traditional height modifying techniques (such as moving an actor farther back in the scene) were not suitable, so in order to shrink the hobbits and dwarves, whilst growing Gandalf, the sets were built in multiple sizes and then they are digitally stitched back together in post production.
This is a sad reality of modern day films, were actors are not actually interacting with each other on set. Despite this, McKellen still does an amazing job.