As the use of virtual and augmented reality applications becomes more common, the need to fully understand how observers perceive spatial relationships grows more critical. One of the key requirements in engineering a practical virtual or augmented reality system is accurately conveying depth and layout. This requirement has frequently been assessed by measuring judgments of egocentric depth. These assessments have shown that observers in virtual reality (VR) perceive virtual space as compressed relative to the realworld, resulting in systematic underestimations of egocentric depth. Previous work has indicated that similar effects may be present in augmented reality (AR) as well.This paper reports an experiment that directly measured egocentric depth perception in both VR and AR conditions; it is believed to be the first experiment to directly compare these conditions in the same experimental framework. In addition to VR and AR, two control conditions were studied: viewing real-world objects, and viewing real-world objects through a head-mounted display. Finally, the presence and absence of motion parallax was crossed with all conditions. Like many previous studies, this one found that depth perception was underestimated in VR, although the magnitude of the effect was surprisingly low. The most interesting finding was that no underestimation was observed in AR.

Many compelling augmented reality (AR) applications require users to correctly perceive the location of virtual objects, some with accuracies as tight as 1 mm. However, measuring the perceived depth of AR objects at these accuracies has not yet been demonstrated. In this paper, we address this challenge by employing two different depth judgment methods, perceptual matching and blind reaching, in a series of three experiments, where observers judged the depth of real and AR target objects presented at reaching distances. Our experiments found that observers can accurately match the distance of a real target, but when viewing an AR target through collimating optics, their matches systematically overestimate the distance by 0.5 to 4.0 cm. However, these results can be explained by a model where the collimation causes the eyes' vergence angle to rotate outward by a constant angular amount. These findings give error bounds for using collimating AR displays at reaching distances, and suggest that for these applications, AR displays need to provide an adjustable focus. Our experiments further found that observers initially reach ∼4 cm too short, but reaching accuracy improves with both consistent proprioception and corrective visual feedback, and eventually becomes nearly as accurate as matching.

A frequently observed problem in medium-field virtual environments is the underestimation of egocentric depth. This problem has been described numerous times and with widely varying degrees of severity, and although there has been considerable progress made in modifying observer behavior to compensate for these misperceptions, the question of why these errors exist is still an open issue. This paper presents the findings of a series of experiments, comprising 103 participants, that attempts to identify and quantify the source of a pattern of adaptation and improved depth judgment accuracy over time scales of less than one hour. Taken together, these experiments suggest that peripheral visual information is an important source of information for the calibration of movement within mediumfield virtual environments.

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Many augmented reality (AR) applications operate within near-field reaching distances, and require matching the depth of a virtual object with a real object. The accuracy of this matching was measured in three experiments, which examined the effect of focal distance, age, and brightness, within distances of 33.3 to 50~cm, using a custom-built AR haploscope. Experiment~I examined the effect of focal demand, at the levels of collimated (infinite focal distance), consistent with other depth cues, and at the midpoint of reaching distance. Observers were too young to exhibit age-related reductions in accommodative ability. The depth matches of collimated targets were increasingly overestimated with increasing distance, consistent targets were slightly underestimated, and midpoint targets were accurately estimated. Experiment~II replicated Experiment~I, with older observers. Results were similar to Experiment~I. Experiment~III replicated Experiment~I with dimmer targets, using young observers. Results were again consistent with Experiment~I, except that both consistent and midpoint targets were accurately estimated. In all cases, collimated results were explained by a model, where the collimation biases the eyes' vergence angle outwards by a constant amount. Focal demand and brightness affect near-field AR depth matching, while age-related reductions in accommodative ability have no effect.