ABSTRACT
A roto artist needs to understand how a computer interpolates the frames between the user-defined keys. When two key frames are created, the position frames between them will be created by the computer based on the relative X and Y values of the two keys. The movement projected by the computer will be linear, that is, a straight line between those two points, evenly distributed over the frames in between. The new motion path of the individual points is still a straight line from each position key frame to the next. Establishing correct placement for key frames within the timeline is almost as important as shape placement in the viewer window. A roto artist will make thousands of key frames when rotoing a single shot. Altering the rate at which that single, solitary key frame interpolates is a terribly inaccurate way to find precise key placement.
