Motion Capture - Part two

Even advanced technique cannot hide unnatural movements.

After the theory behind 'motion capture', where we wrote about last month, it's now time to look at how it actually works. Therefore we visited Motek, an Amsterdam based company that specialized itself over the last years in the use of motion capture.

By entrance we got a friendly welcome by Guido van Nispen and after a brief introduction we started of with the most logic question. Why did they change for the making of digital animations from the established key frame technique to motion capture. There are different reasons for that, Guido starts. First of all key framing is a time consuming business. In most cases motion capture turned out to give much faster results. Therefore of course it is also much cheaper. But the second and most important point is that motion capture gives a much more natural result then key framing which is of course the prime goal: to simulate natural movements. And therefore you need to go as far as possible within reasons. The last bit may sound vague but I 'll give an example. At a certain moment while we were working on a computer game we had to simulate the movements of a soldier walking through rough terrain carrying 50 kilo on his back. First we tried to force the actor to walk as if he had 50 kilo on his back, but that didn't gave the right result. Then we actually did put 50 kilos on his back and it did work.

Woman as man.

In the Motek studio people are busy doing captures for the television series "Cafe de Wereld" part of the TV program VARA Laat! The studio is filled with computers, tv-screens, cameras and lots of cables. It does look very impressive. On the set are two actresses doing a scene. Both are wearing a tight black bodysuit. On the suits are sensors. Eleven to be precise. Enough to get the wanted result. The suits are tailor made on the exact measurements of the actors. It is very important that the sensors on the suits do not move. A few millimeters of deviation can lead to some strange results. The sensors are connected by cables to the computers of the operators, like the director. Result of this all is that all the movements from the actors are being showed realtime on the screens. The digital representation is in this case also a female. Coincidence? "Well yes", Guido explains. "On the contrary it doesn't matter if a man or a woman plays the roll of a specific character. The differences in movement are for an outsider hardly recognizable. Besides that someone who watches or playing a game doesn't care about that. When you play a game, you're absolutely not interested in the person that is responsible for the movements of your opponent. There are special cases, were you reach the borders of the physical possibilities of the actors or actresses. A fragile actress could perform for a huge commando guy but in the end you will see the result. The contrast is to big. We tried once to compensate this by using tricks like putting heavy weights underneath the actresses arms but this was not enough to look real.

Follow up

The rest of the team is busy to process all the input that comes in. Guido: "The common idea with motion capture is that all the work is done by the actors and actresses but that is a misunderstanding. The final process of the input on the computer and the post processing might not be underestimated. You can say that during a motion capture session 20% of the work is done by the actors en 80 % by the people behind the computers. Besides the Cafe the Wereld set there is a round platform in the studio. 'We use this for the simulation of movements", Guido says. Think of the movements of a car riding on a bumpy road. In this case the coordinates and movements of the real car are being registered and put into the software that controls the motion platform. The platform will move exactly as the car did. Then we put someone on the platform in a simulated car ride on a bumpy road and it will feel very natural. Guido cannot underline enough the importance and possibilities of motion capture. In this case it means that as well as the person on the platform as the platform itself try to create a natural as possible situation. But we forgot about the most important aspect and that is the imagination of the actor or actress. If the actor or actress has no affinity with the character he of she represents the result will never be optimal. A very good example for that is the character of Gollum from the movie The Lord Of the Rings. Actor Andy Serkis had great affinity with the character of Gollum and than it looks immediately very natural. Technique is important, but in the end it is still so that even technique cannot hide unnatural movements.