Motion capture (or mo-cap) is one of the most dynamic of all forms of computer interfacing with a human. Not only if it hadn't been for this procedure would the current entertainment industry as we know it be completely different, but it's been applied for military, sports and medical purposes also.
Films such as Lord of the Rings and the recent version of King Kong would never have appeared as realistic or even possible until this technique had been invented and applied to the movie world. Interestingly, both mentioned titles owe a great deal to the actor Andy Serkis, who played Gollum in the Lord of the Rings trilogy and Kong (as well as the cook) in King Kong.
The process of motion capture involves an actor's face and body being covered with a series of 'dots' at joints around the body, which specialist cameras detect the movement of and apply to rendered models, which can then be digitally added to the scene at post-production. The end result of these movements and expressions offer a much improved, aesthetically satisfying and realistic character on-screen than could be achieved currently by computer alone. For the role of Gollum, Andy had to really suffer for his art - spending three years on all fours and additional time in post-production to ensure the facial expressions were truly captured.
Computers are brilliant at assisting with the development of the world around us, but one subtly overlooked issue with them is that they can only be as good as the programmer as none at this stage show any true capability to learn and evolve - particularly socially (much like the programmer). This only compounds the fact that artificial intelligence is no substitute for natural stupidity.
Speaking of stupidity, one funny instance of the IT gremlins wreaking havoc took place during the scene at Lord of the Ring's second film: The Two Towers. The programme used to give the characters on screen artificial intelligence backfired in massive proportions. During the battle at Helm's Deep, the massive army of Orcs and Uru'khai fled as a routed force rather than attack. Programmers had to re-write the artificial intelligence to ensure they acted as instructed, rather than behave 'naturally'.
The fantastic scenes which grace the screen from start to finish make this trilogy in particular an immensely immersive and very enjoyable work of art in so many ways. Tolkien's deeply descriptive and vivid depictions were beautifully brought to life through the eyes of its director (Peter Jackson) and the talents of the art team and computer programmers who laboured on this project. Even though this trilogy is now the best part of a decade old, it's still a good benchmark for others to try and equal or better today.