Effects of Character Geometric Model on Perception of Sign Language Animation

This paper reports a study that aimed to determine whether character geometric model (i.e. segmented vs. seamless) has an effect on how animated signing is perceived by viewers. Additionally, the study investigated whether the geometric model affects perception at varying degrees of linguistic complexity-specifically handshape complexity. We modeled and animated two polygonal 3D characters: Torrents, one seamless mesh, and Robby, a fully segmented avatar. Both characters had similar geometrical proportions, identical skeletal systems, similar visual styles and color schemes, and met standards of good character design. Each signed 60 stimulus signs, divided into three groups-those with simple (group I), moderately complex (group II), and complex (group III) handshapes according to factors established in the linguistic literature. 53 participants, who learned ASL by age 5, viewed animated clips in random order via web survey. They (1) identified the sign (if recognizable), and (2) rated its realism using a 5-point Likert scale. Findings show that the seamless avatar (Torrents) was rated highest, and simple handshapes were rated higher than moderately complex and complex ones. The interaction between character and handshape complexity was also significant. For Robby (more than for Torrents), ratings decreased as handshape complexity increased. The lower ratings for Robby could indicate a preference for seamless, deformable characters over segmented ones, especially in signs with complex handshapes.