Evaluation of Body-centric Locomotion with Different Transfer Functions in Virtual Reality

Body-centric locomotion allows users to navigate virtual environments with body parts (e.g. head tilt, arm swing or torso lean). Transfer functions are an important determinant of the locus of such a locomotion method. However, there is little known about the effects of transfer functions on virtual locomotion with different body parts. In this work, we selected four typical transfer functions (linear function: L, power function: P, a piecewise function with constant and linear functions: CL, and a piecewise function with constant and power functions: CP) and four body parts (head, arm, torso, and knee) from existing works, and conducted an experiment to evaluate their effects on virtual locomotion under three distances (5, 10, and 15 m) in Virtual Reality (VR). Results show that (1) CP function generally led to the longest task time with a low rate of failed trials, while CL function had the shortest task time with a high rate of failed trials; (2) body parts significantly affected the rate of failed trials, but not task time and final position offset. Head and torso resulted in the lowest and highest rate of failed trials respectively; (3) body parts did not differ in User Experience Questionnaire-Short (UEQ-S), UEQ-S Pragmatic and UEQ-S Hedonic. L was rated as the highest score for UEQ-S, UEQ-S Pragmatic and UEQ-S Hedonic, but CP had the lowest score. According to the results, we provide implications of designing body-centric locomotion with different transfer functions in VR.