Exaggerating Character Motions Using Sub‐Joint Hierarchy

Abstract

Motion capture cannot generate cartoon-style animation directly. We emulate the rubber-like exaggerations common in traditional character animation as a means of converting motion capture data into cartoon-like movement. We achieve this using trajectory-based motion exaggeration while allowing the violation of link-length constraints. We extend this technique to obtain smooth, rubber-like motion by dividing the original links into shorter sub-links and computing the positions of joints using Bézier curve interpolation and a mass-spring simulation. This method is fast enough to be used in real time.

Velocity Skinning for Real‐time Stylized Skeletal Animation

“…Simpler dynamic deformers have also been explored, from early work coupling particles and implicit surfaces to achieve cartoonphysics effects [OM94], through extra bones attached to the skeleton to model flesh oscillations [LCa05], or the use of sub‐bones connected by springs to achieve curvy, dynamic shapes [KL08]. Muscles approximations have also been developed both in explicit [RL13] and implicit [RRC*18] formulations.…”

Velocity Skinning for Real-time Stylized Skeletal Animation

“…Simpler dynamic deformers have also been explored, from early work coupling particles and implicit surfaces to achieve cartoonphysics effects [OM94], through extra bones attached to the skeleton to model flesh oscillations [LCa05], or the use of sub-bones connected by springs to achieve curvy, dynamic shapes [KL08]. Muscles approximations have also been developed both in explicit [RL13] and implicit [RRC * 18] formulations.…”

Adding Cartoon-Like Motion to Realistic Animations

“…In contrast, Kwon and Lee developed a system that allows animators to add squash and stretch effects (akin to rubber) to existing motion capture data [50]. They accomplish this by exaggerating joint-trajectories and modifying the inherent skeletonstructure of the character to allow for cartoon-like limb squishing and stretching.…”

“…Many of the research projects presented above focus on the system functionality and performance without any mention of the human factor involved [9], [50]. For example, the cartoon animation filter [11] does not describe any method of system interaction.…”