Effects of Full-Body Tracking on Embodiment in Virtual Reality

The focus of the research presented here is on the embodying of a virtual avatar in immersive virtual reality (VR). The sense of embodiment is towards a virtual avatar can be described and measured with three factors; self-location, agency, and body ownership. These three sub-factors are typically improved through a variety of stimulation techniques. The research presented explores visuomotor synchrony, tracking fidelity, and avatar presentation stimulation techniques for inducing stronger virtual embodiment. Full-body tracking techniques are explained in detail, and different techniques are used below to provide visuomotor synchrony between user movements and avatar movements. We will initially present and discuss a full-body tracking solution comprised of inertial measurement units (IMUs). This system uses forward kinematics, or each joint orientation and position building off the previous joint in a chain, to provide body segment tracking for each main rigid body segment of a body. An initial training application using the IMU-based tracking solution is discussed along with the benefits and limitations of the system. A shift in availability of consumer virtual reality hardware also created a shift in the hardware used in our research. With the onset of new tracking options integrated with VR development software, we will later present and discuss research investigating embodiment performed with an off-the-shelf consumer virtual reality system, the HTC Vive and additional trackers. This system demonstrates the use of inverse-kinematics (IKs) to estimate the untracked joints from a user’s body. We use this system to investigate avatars, body tracking fidelity, and embodiment in immersive virtual reality. Methods for measuring embodiment are discussed and a self-report measure, the Embodiment Short Questionnaire (ESQ), is presented and initially validated.