Perceived Naturalness of Interpolation Methods for Character Upper Body Animation

Xingyu Lei, Nicoletta Adamo-Villani, Bedrich Benes, Zhiquan Wang, Zachary Meyer, Richard E. Mayer, Alyssa P. Lawson

Abstract: We compare the perceived naturalness of character animations generated using three interpolation methods: linear Euler, spherical linear quaternion, and spherical spline quaternion. While previous work focused on the mathematical description of these interpolation types, our work studies the perceptual evaluation of animated upper body character gestures generated using these interpolations. Ninety-seven participants watched 12 animation clips of a character performing four different upper body motions: a beat gesture, a deictic gesture, an iconic gesture, and a metaphoric gesture. Three animation clips were generated for each gesture using the three interpolation methods. The participants rated their naturalness on a 5-point Likert scale. The results showed that animations generated using spherical spline quaternion interpolation were perceived as significantly more natural than those generated using the other two interpolation methods. The findings held true for all subjects regardless of gender and animation experience and across all four gestures.