Improved Standard-Based Motion Parallax Measurement in Mixed Reality

Motion parallax refers to the perceived difference in motion of objects at varying distances from the observer; objects that are closer appear to move faster, and vice versa. This depth cue is crucial for humans in judging distance in physical surroundings. However, in virtual environments, the limited field of view of display devices makes it difficult for humans to perceive the same level of motion parallax as they can in the physical environment. Recent studies have aimed to improve users gaining motion parallax for a more realistic virtual environment, but there is currently no standardized method to conclude a large amount of data for evaluating and comparing their proposed techniques. In this paper, we first propose an improved formula with normalization as a motion parallax evaluation standard and evaluate it by conducting motion parallax experiments using a Microsoft HoloLens 2 device. The experiments consisted of a standard one with different relative moving distances and distance reporting methods (blind walking and oral reporting), and another using an X-ray vision system that helps users see through physical obstacles, potentially providing motion parallax. The aim was to assess the effectiveness of our proposed standard and evaluate whether the proposed conditions influence users' ability to estimate distance by utilizing motion parallax.