Another use of squash and stretch is to help relieve the disturbing effect of strobing that happens with very fast motion because sequencial positions of an object become spaced far apart. When the action is slow enough, the object's positions overlap, and the eye smooths the motion out. (figure 4a) However, as the speed of the action increases, so does the distance between positions. When the distance becomes far enough that the object does not overlap from frame to frame, the eye then begins to perceive separate images. (figure 4b) Accurate motion blur is the most realistic solution to this problem of strobing, [8,9] but when motion blur is not available, squash and stretch is an alternative: the object should be stretched enough so that its positions do overlap from frame to frame (or nearly so), and the eye will smooth the action out again. (figure 4c)
In 3D keyframe computer animation, the scale transformation can be used for squash and stretch. When scaling up in Z, the object should be scaled down in X and Y to keep the volume the same. Since the direction of the stretch should be along the path of action, a rotational transformation may be required to align the object along an appropriate axis.