On the Plausibility of Virtual Body Animation Features in Virtual Reality

Abstract

We present two experiments to assess the relative impact of different levels of body animation fidelity on plausibility illusion (Psi). The first experiment presents a virtual character that is not controlled by the user (n = 13), while the second experiment presents a user-controlled virtual avatar (n = 24, all male). Psi concerns how realistic and coherent the events in a virtual environment look and feel and is part of Slater's proposition of two orthogonal components of presence in virtual reality (VR). In the experiments, the face, hands, upper and lower bodies of the character or self-avatar were manipulated to present different degrees of animation fidelity, such as no animation, procedural animation, and motion captured animation. Participants started the experiment experiencing the best animation configuration. Then, animation features were reduced to limit the amount of captured information made available to the system. Participants had to move from this basic animation configuration towards a more complete one, and declare when the avatar animation realism felt equivalent to the initial and most complete configuration, which could happen before all animation features were maxed out. Participants in the self-avatar experiment were also asked to rate how each animation feature affected their sense of control of the virtual body. We found that a virtual body with upper and lower body animated using eight tracked rigid bodies and inverse kinematics (IK) was often perceived as equivalent to a professional capture pipeline relying on 53 markers. Compared to what standard VR kits in the market are offering, i.e. a tracked headset and two hand controllers, we found that foot tracking, followed by mouth animation and finger tracking, were the features that added the most to the sense of control of a self-representing avatar. In addition, these features were often among the first to be improved in both experiments.

A Separate Reality: An Update on Place Illusion and Plausibility in Virtual Reality

“…Psi is beginning to be extensively studied e.g. (Bergström et al, 2017;Skarbez et al, 2017;GalvanDebarba et al, 2020). The important point of this is that when both PI and Psi operate people tend to respond realistically to situations and events in the VR, even though they know for sure that these are illusions and not reality.…”

“…Fribourg et al (2020) turned the method towards evaluation of body ownership rather than PI or Psi. GalvanDebarba et al (2020) studied Psi in relation to body animation features. Clearly the same method could be used for the evaluation of different subjective responses, not only PI of Psi, which we turn to next.…”

Animation Fidelity in Self-Avatars: Impact on User Performance and Sense of Agency

“…Previous work has demonstrated the importance of having a selfavatar that moves in sync with the user [9,10,33]. If we focus on the overall movement without further interaction with the virtual world, current animation techniques based on IK from sparse tracking data may suffice.…”

Application of eye-tracking systems integrated into immersive virtual reality and possible transfer to the sports sector - A systematic review

“…Using VR simplifies research by minimizing costs, time-consuming processes, accessing the needed physical surroundings. An additional benefit of VR is the synchronization with other measurement systems such as eye-tracking (ET) [16,67] or infrared motion capturing systems [24,66]. With that, extensions of possibilities arise that cannot be implemented in reality, such as occlusion of one's body parts [66] or changing and expanding body properties [33,73].…”