Examining eye vergence angle in optical see-through augmented reality

Abstract

A primary objective of optical see-through (OST) Augmented Reality (AR) systems is to enable users to perceive the depth of AR objects with the same accuracy as they perceive the depth of real-world objects. Previous studies have shown that individuals often make depth judgments that either underestimate or overestimate the depth of AR objects compared to real-world objects. Recently, OST AR devices have incorporated eye-tracking technology, offering the opportunity to objectively measure and investigate the depth-dependent components of the human visual system (e.g., eye vergence angle) while perceiving the depth of real and AR objects. This paper measures and examines the eye vergence angle (EVA) for both real and AR objects at four different depths (0.35 m, 0.75 m, 1.5 m, and 4.0 m) using integrated eye-tracking systems of the two commercial devices: Microsoft HoloLens 2 and Magic Leap 2. The experiment considered a four-alternative forced-choice visual discrimination task with a repeated-measures design, involving 24 participants. Our findings showed that subjective (verbal estimation) and objective (EVA) measures of depth perception were consistent with the depth of both real and AR objects in both OST AR devices. The results demonstrated individual differences in EVA for each device across various depths. No difference in EVA was identified between real and AR objects. Additionally, the EVA range differs between the OST AR devices for each depth. These findings indicate that objective EVA measurements cannot be generalized across different OST AR devices and individuals.