Tweens are Just Averages
Here’s a key aspect to using the Tweening feature: When preparing to create Tweens, remember that FrameForge is not psychic; it can’t predict how you want a shot to work. All it can do is calculate the average change or changes between two selected Key Frames, then set up the tween shot(s) according to those averages. For example, consider the following two frames:
FIG I: A pair of Key Frames
A car enters the set on the right (Key Frame A), and exits the set on the left (Key Frame B); at the same time, the driver turns her head to look at the camera. If you create a single Tween, it will place the car exactly 50% of the way between A and B, with the driver’s head turned exactly halfway between its positions in A and B. Similarly, the camera, which is also moving, gets repositioned halfway between A and B. Here's how the lone Tween looks:
FIG II: A single tween
See? There is a fifty percent change in the position of everything that moved between shots A and B.
By the same token, if you were to generate three Tweens between A and B, the car and camera would both move 25% of the total distance in each frame...and so on, for however many Tweens you create.
Why is this important? Sometimes (like in the example above) it's not. But other times...well, see the articles on "The Object Problem" and "The Relative Positions Problem" for more.