Motion imitation with a handheld camera

In this paper, we present a novel method to extract motion of a dynamic object from a video that is captured by a handheld camera, and apply it to a 3D character. Unlike the motion capture techniques, neither special sensors/trackers nor a controllable environment is required. Our system significantly automates motion imitation which is traditionally conducted by professional animators via manual keyframing. Given the input video sequence, we track the dynamic reference object to obtain trajectories of both 2D and 3D tracking points. With them as constraints, we then transfer the motion to the target 3D character by solving an optimization problem to maintain the motion gradients. We also provide a user-friendly editing environment for users to fine tune the motion details. As casual videos can be used, our system, therefore, greatly increases the supply source of motion data. Examples of imitating various types of animal motion are shown.