Augmenting Hand Animation with Three-dimensional Secondary Motion
Secondary motion, or the motion of objects in response to that of the primary character, is widely used to amplify the audience’s response to the character’s motion and to provide a connection to the environment. These three- dimensional (3D) effects are largely passive and tend to be time consuming to animate by hand, yet most are very effectively simulated in current animation software. In this paper, we present a technique for augmenting hand-drawn animation of human characters with 3D physical effects to create secondary motion. In particular, we create animations in which hand-drawn characters interact with cloth and clothing, dynamically simulated balls and particles, and a simple fluid simulation. The driving points or volumes for the secondary motion are tracked in two dimensions, reconstructed into three dimensions, and used to drive and collide with the simulated objects. Our technique employs user interaction that can be reasonably integrated into the traditional animation pipeline of drawing, cleanup, inbetweening, and coloring.
Thank you to Glen Keane, Tom LaBaff and Travis Blaise for providing the input animations, and to Justin Macey and Moshe Mahler for help with motion capture and video. Thanks also to Autodesk for their donation of the 3D animation and rendering package Maya, and to Disney Research for funding.