Game Development Reference
12 Motion capture
The early pioneers of animation spent a lot of time studying motion. Some
chose to film the actors performing the motions that they were intending
to animate. In this way, the complexity of the actions could be analysed
frame by frame. Some animators went even further and simply traced this
motion directly onto their animation paper. This technique, known as roto-
scoping, was the basis of the animation of both Snow White and Prince
Charming in the legendary Disney film.
Roto-scoping has a digital equivalent, motion capture or mocap for
short. Many animation purists dislike roto-scoping and for largely the
same reason they also dislike mocap. The reasoning behind their
prejudice is that a very well drawn animation scene has a dynamic that
roto-scoping can never achieve, simply because the human body is not
capable of the dynamics involved. Since mocap files are captured from
the performance of a real being, they can also suffer from this limitation.
When working with digital data like mocap files, however, animators can
be provided with tools that allow them to use their skills to enhance the
data. Using such tools the animator can enjoy all the benefits inherent in
mocap, which provides a plausible illusion of life, while not suffering from
the problems of stiffness that can be a disappointing side-effect of roto-
scoping. In this chapter we are going to look first at the principal methods
used to capture motion data. We will look at how with a little engineering
Figure 12.1 A drawn roto-scoped sequence.