Dead Eye Syndrome

Most of us probably know by now of the issues faced in most video games and films when it comes to using mo-cap technology... even to this day, and that is the dead eye syndrome, where characters somehow end up with dead, soulless eyes that completely ruins the overall look of the character (Regardless of how many detailed textures are used when modelling them and how dynamic their body animations can be). And, even to this day, "The Polar Express" probably remains one of the best known examples of that unfortunate dilemma. 

"The Polar Express" is a 2004 American motion capture computer-animated musical Christmas fantasy film based on the children's book of the same title by Chris Van Allsburg. The film featured human characters animated using the live action performance capture technique, with the exception of the dancing waiters who dispense hot chocolate on the train, before their feats were impossible for live actors to achieve.

Despite the film's gorgeous visuals and decent camera works (Thanks to Robert Zemeckis), many people were still deterred over how fake-looking and puppet-like the human characters were in the film. These characters (Especially the poor Conductor) came off so creepy that what should have been a promising holiday classic instead became a failed experiment that most people constantly made fun of or avoided completely to this day. 

The actors can't be blamed for this part as we can clearly see in the above image just how much energy Tom Hanks puts into his performance during his sessions with the mo-cap gear, it is unfortunate to see that all of that is somehow lost in the final animation. And this includes their overall facial expression, maybe a tiny bit of attention could have been taken away from those terrifying eyes had they actually tried to make the rest of the character's face work, but for some reason, their mouths and cheeks seem just as lame.

Not to say that it is a simple mistake that could be fixed but, did the animators even try in the first place? Were they just more invested in body movements than the faces of the characters? Considering the number of close ups in the movies, they honestly should have paid the same amount of attention to the character's expression as they did with the rest...

Gollum from Peter Jackson's "Lord of the Rings" was animated with the utmost care, with Peter Jackson and his crew paying close attention to every little detail on the cursed hobbit when mo-capping and animating him. In the end, people at Weta Digital ended up creating  a program that dealt with facial expressions, lining up digital skin to Andy Serkis' facial details when he created a particular expression. Weta would after that tweak and polish those expressions a little more to make sure they fit the appropriate scenes.

Mo-cap is good for picking up subtle things that the body does for a particular motion that maybe the animator would not realise (Which bears a little similarity to rotoscoping if you think about it... seeing that by drawing over every little detail caught from the live action reference , the movements of the characters will be far more intricate as compared to when they are drawn from scratch). It can also help further the production, simplifying some motions that animators could have had a hard time working on. 

Still, it is the face that still requires the most aid and attention of animators, while other forms of new technology have been developed over the years to record the faces of the actors in hopes of giving them more realism, energy and of course life (Such as the MotionScan used for "L.A Noire"), it is clear that this still remains a challenging aspect in computer animation, and may remain so for years to come.