Abstract: Motion is the center of attention in many applications of computer graphics. Skeletal motion for articulated characters can be processed and altered in a variety of ways to increase the versatility of each motion clip. However, analogous techniques have not yet been developed for free-form deforming surfaces like cloth and faces. Given the time-consuming nature of producing each free-form motion clip, the ability to alter and reuse free-form motion would be very desirable. We present a novel method for processing free-form motion that opens up a broad range of possible motion alterations including motion blending, keyframe insertion, and temporal signal processing. Our method is based on a simple yet powerful differential surface representation that is invariant under rotation and translation and which is well suited for surface editing in both space and time.