Interpolation Options

The beauty of keyframes is that they save you work. If you set the keyframes, Premiere calculates the frames in between, a process known as interpolation. You won't find the word, "interpolation" in Premiere's documentation, but you will encounter the term in other animation programs, including Adobe's own After Effects. No harm in getting used to it now. By default, Premiere calculates the values between keyframes using a linear progression. Spatially, this linear interpolation method means that a clip proceeds from one position to the next in a straight line. Temporally, linear interpolation causes the clip to move from one position to the next at a constant rate, or speed.

As you might guess, simple linear interpolation can make motion seem somewhat mechanical. To make motion appear more natural, you would have to set many more keyframes—and in effect defeat their labor-saving purpose. Fortunately, Premiere offers a few other, more sophisticated interpolation methods. Temporally, this means motion can accelerate or decelerate from one keyframe to the next. Spatially, interpolation options allow movement to follow a smoother, rounder course through keyframe positions.