Interpolation-Based Animation - Computer Animation: Algorithms and Techniques - page 113

key frame key frame

Simple key frames in which each curve of a frame has the same number of points as
its counterpart in the other frame

key frame key frame

Keys and three intermediate frames with linear interpolation of a single point (with reference lines
showing the progression of the interpolation in x and y )

FIGURE 4.2
Simple key and intermediate frames. A specific point is identified in both key frames; the interpolation of the point
over intermediate frames is shown with auxiliary lines showing its relative placement in the frames.

FIGURE 4.3
Object splatting against a wall. The shape must be interpolated from the initial egg shape to the splattered shape.

If both curves were generated with the same type of interpolation information, for example, each is
a single, cubic Bezier curve, then intermediate curves could be generated by interpolating the control
points and reapplying the Bezier interpolation. Another alternative would be to use interpolating func-
tions to generate the same number of points on both curves. These points could then be interpolated on a
point-by-point basis. Although these interpolations get the job done, they might not provide sufficient
control to a user who has specific ideas about how the intermediate curves should look.