Distances In Virtual Environments Research Articles

Social rather than physical crowding reduces the required interpersonal distance in virtual environments.

Interpersonal distance plays an important role in human social interaction. With the increasing usage of virtual reality in social interaction, people's interpersonal distance in virtual space attracts great attention. It remains unclear whether and to what extent human-required interpersonal distance is altered by crowded virtual scenes. In this study, we manipulated crowd density in virtual environments and used the classical stop-distance paradigm to measure required interpersonal distances at different crowd densities. We found that people's required interpersonal distance decreased with increased social crowdedness but not with physical crowdedness. Moreover, the decrease of two types of interpersonal distance was associated with the globally averaged crowd density rather than local crowd density. The reduction is not due to the imitation of other virtual humans in the crowd. Moreover, we developed a model to describe the quantitative relationships between the crowdedness of the environment and the required interpersonal distance. Our finding provides insights into designing user-friendly virtual humans in metaverse virtual worlds.

Distance Perception in the Oculus Quest and Oculus Quest 2

Distances in virtual environments (VEs) viewed on a head-mounted display (HMD) are typically underperceived relative to the intended distance. This paper presents an experiment comparing perceived egocentric distance in a real environment with that in a matched VE presented in the Oculus Quest and Oculus Quest 2. Participants made verbal judgments and blind walking judgments to an object on the ground. Both the Quest and Quest 2 produced underperception. Verbal judgments in the VE were 82% and 75% of the object distance, in contrast with real world judgments that were 94% of the object distance. Blind walking judgments were 68% and 70% of object distance in the Quest and Quest 2, respectively, compared to 88% in the real world. This project shows that significant underperception of distance persists even in modern HMDs.

Obstacles Affect Perceptions of Egocentric Distances in Virtual Environments

Distance perception in humans can be affected by oculomotor and optical cues and a person’s action capability in a given environment, known as action-specific effects. For example, a previous study has demonstrated that egocentric distance estimation to a target is affected by the width of a transparent barrier placed in the intermediate space between a participant and a target. However, the characteristics of a barrier’s width that affect distance perception remain unknown. Therefore, we investigated whether visual and tactile inputs and actions related to a barrier affect distance estimation to a target behind the barrier. The results confirmed previous studies by demonstrating that visual and tactile presentations of the barrier’s width affected distance estimation to the target. However, this effect of the barrier’s width was not observed when the barrier was touchable but invisible nor when the barrier was visible but penetrable. These findings indicate the complexity of action-specific effects and the difficulty of identifying necessary information for inducing these effects.

Comparison of Two Methods for Improving Distance Perception in Virtual Reality

Distance is commonly underperceived in virtual environments (VEs) compared to real environments. Past work suggests that displaying a replica VE based on the real surrounding environment leads to more accurate judgments of distance, but that work has lacked the necessary control conditions to firmly make this conclusion. Other research indicates that walking through a VE with visual feedback improves judgments of distance and size. This study evaluated and compared those two methods for improving perceived distance in VEs. All participants experienced a replica VE based on the real lab. In one condition, participants visually previewed the real lab prior to experiencing the replica VE, and in another condition they did not. Participants performed blind-walking judgments of distance and also judgments of size in the replica VE before and after walking interaction. Distance judgments were more accurate in the preview compared to no preview condition, but size judgments were unaffected by visual preview. Distance judgments and size judgments increased after walking interaction, and the improvement was larger for distance than for size judgments. After walking interaction, distance judgments did not differ based on visual preview, and walking interaction led to a larger improvement in judged distance than did visual preview. These data suggest that walking interaction may be more effective than visual preview as a method for improving perceived space in a VE.

Misperception of egocentric distances in virtual environments: More a question of training than a technological issue?

Findings from virtual reality applications in general and driving or flight simulators in particular, are frequently generalized to the study of human behavior. Thus, it is crucial to ensure that the virtuality of the experimental setup has little or no effect on perception of space and motion. Most studies show that observers immersed in virtual environments (VE) perceive virtual space as compressed relative to the real world, resulting in systematic underestimations of egocentric distance. Parallax and stereopsis, known to be important depth cues for distance perception, at least for short distances, are rarely used together in driving simulators, so their interactive role during driving tasks is still not clear. Inter-individual differences in misperception are also referred to, though few studies have explored this. The aim of this study was, first, to determine whether egocentric distance perception in driving simulation depends on two depth cues, binocular disparity and motion parallax, and, second, to examine the effect of inter-individual differences. Several conditions were tested, both with and without stereoscopic vision of the scene and/or motion parallax of the head. We focused first on a range of long distances, 40–80 m (Experiment 1) and subsequently widened the range to distances from 5 to 80 m, thereby including short distances where stereopsis should be more relevant (Experiment 2). The study reveals great inter-individual variability, clearly distinguishing two participant profiles. However, results suggest that such differences do not depend on the availability of motion parallax and stereoscopic vision.The findings also show that an initial familiarization phase, under conditions similar to those of the experiments, can be predictive of participants’ perceptual behavior.

Rescaling of perceived space transfers across virtual environments.

Research over the past 20 years has consistently shown that egocentric distance is underperceived in virtual environments (VEs) compared with real environments. In 2 experiments, judgments of object distance (Experiment 1) and object size (Experiment 2) improved after a brief period of walking through the VE with continuous visual feedback. Whereas improvement of blind-walking distance judgments could be attributable to recalibration of walking, improvement in perceived size is considered evidence for rescaling of perceived space, whereby perceived size and distance increased after walking interaction. Furthermore, improvements in judged distance and size transferred to a new VE. Distance judgments, but not size judgments, continued to improve after additional walking interaction in the new VE. These results have theoretical implications regarding the effects of walking interaction on perceived space, and practical implications regarding methods of improving perceived distance in VEs. (PsycINFO Database Record

Virtual arm׳s reach influences perceived distances but only after experience reaching

Considerable empirical evidence has shown influences of the action capabilities of the body on the perception of sizes and distances. Generally, as one׳s action capabilities increase, the perception of the relevant distance (over which the action is to be performed) decreases and vice versa. As a consequence, it has been proposed that the body׳s action capabilities act as a perceptual ruler, which is used to measure perceived sizes and distances. In this set of studies, we investigated this hypothesis by assessing the influence of arm׳s reach on the perception of distance. By providing participant with a self-representing avatar seen in a first-person perspective in virtual reality, we were able to introduce novel and completely unfamiliar alterations in the virtual arm׳s reach to evaluate their impact on perceived distance. Using both action-based and visual matching measures, we found that virtual arm׳s reach influenced perceived distance in virtual environments. Due to the participants׳ inexperience with the reach alterations, we also were able to assess the amount of experience with the new arm׳s reach required to influence perceived distance. We found that minimal experience reaching with the virtual arm can influence perceived distance. However, some reaching experience is required. Merely having a long or short virtual arm, even one that is synchronized to one׳s movements, is not enough to influence distance perception if one has no experience reaching.

Recalibration of Perceived Distance in Virtual Environments Occurs Rapidly and Transfers Asymmetrically Across Scale

Distance in immersive virtual reality is commonly underperceived relative to intended distance, causing virtual environments to appear smaller than they actually are. However, a brief period of interaction by walking through the virtual environment with visual feedback can cause dramatic improvement in perceived distance. The goal of the current project was to determine how quickly improvement occurs as a result of walking interaction (Experiment 1) and whether improvement is specific to the distances experienced during interaction, or whether improvement transfers across scales of space (Experiment 2). The results show that five interaction trials resulted in a large improvement in perceived distance, and that subsequent walking interactions showed continued but diminished improvement. Furthermore, interaction with near objects (1-2 m) improved distance perception for near but not far (4-5 m) objects, whereas interaction with far objects broadly improved distance perception for both near and far objects. These results have practical implications for ameliorating distance underperception in immersive virtual reality, as well as theoretical implications for distinguishing between theories of how walking interaction influences perceived distance.

The perception of egocentric distances in virtual environments - A review

Over the last 20 years research has been done on the question of how egocentric distances, i.e., the subjectively reported distance from a human observer to an object, are perceived in virtual environments. This review surveys the existing literature on empirical user studies on this topic. In summary, there is a mean estimation of egocentric distances in virtual environments of about 74% of the modeled distances. Many factors possibly influencing distance estimates were reported in the literature. We arranged these factors into four groups, namely measurement methods, technical factors, compositional factors, and human factors. The research on these factors is summarized, conclusions are drawn, and promising areas for future research are outlined.

More than just perception–action recalibration: Walking through a virtual environment causes rescaling of perceived space

Egocentric distances in virtual environments are commonly underperceived by up to 50% of the intended distance. However, a brief period of interaction in which participants walk through the virtual environment while receiving visual feedback can dramatically improve distance judgments. Two experiments were designed to explore whether the increase in postinteraction distance judgments is due to perception-action recalibration or the rescaling of perceived space. Perception-action recalibration as a result of walking interaction should only affect action-specific distance judgments, whereas rescaling of perceived space should affect all distance judgments based on the rescaled percept. Participants made blind-walking distance judgments and verbal size judgments in response to objects in a virtual environment before and after interacting with the environment through either walking (Experiment 1) or reaching (Experiment 2). Size judgments were used to infer perceived distance under the assumption of size-distance invariance, and these served as an implicit measure of perceived distance. Preinteraction walking and size-based distance judgments indicated an underperception of egocentric distance, whereas postinteraction walking and size-based distance judgments both increased as a result of the walking interaction, indicating that walking through the virtual environment with continuous visual feedback caused rescaling of the perceived space. However, interaction with the virtual environment through reaching had no effect on either type of distance judgment, indicating that physical translation through the virtual environment may be necessary for a rescaling of perceived space. Furthermore, the size-based distance and walking distance judgments were highly correlated, even across changes in perceived distance, providing support for the size-distance invariance hypothesis.

Tuning Self-Motion Perception in Virtual Reality with Visual Illusions

Motion perception in immersive virtual environments significantly differs from the real world. For example, previous work has shown that users tend to underestimate travel distances in virtual environments (VEs). As a solution to this problem, researchers proposed to scale the mapped virtual camera motion relative to the tracked real-world movement of a user until real and virtual motion are perceived as equal, i.e., real-world movements could be mapped with a larger gain to the VE in order to compensate for the underestimation. However, introducing discrepancies between real and virtual motion can become a problem, in particular, due to misalignments of both worlds and distorted space cognition. In this paper, we describe a different approach that introduces apparent self-motion illusions by manipulating optic flow fields during movements in VEs. These manipulations can affect self-motion perception in VEs, but omit a quantitative discrepancy between real and virtual motions. In particular, we consider to which regions of the virtual view these apparent self-motion illusions can be applied, i.e., the ground plane or peripheral vision. Therefore, we introduce four illusions and show in experiments that optic flow manipulation can significantly affect users' self-motion judgments. Furthermore, we show that with such manipulations of optic flow fields the underestimation of travel distances can be compensated.

Effects of scale change on distance perception in virtual environments

We conducted a series of experiments to investigate effects of scale changes on distance perception in virtual environments. All experiments were carried out in an HMD. Participants first made distance estimates with feedback in a virtual tunnel (adaptation) and then made distance estimates without feedback in a differently-scaled virtual environment (test). We examined several types of scale changes, including changing the size of (1) the tunnel, (2) the targets, and (3) the separation of the two targets. Changes in target size always affected distance estimates at test. When the targets became smaller, participants overshot distance and when the targets became larger, participants undershot distance. Changes in the size of the tunnel or the separation between the targets (without a change in the size of the targets) had a minimal effect on distance estimates. These results indicate that distance estimates at test were strongly influenced by familiar size cues for distance. The discussion focuses on the stability of calibration processes and mechanisms for cue integration for perceiving distance in virtual environments.

Can exocentric direction be dissociated from its exocentric distance in virtual environments?

We conducted two psychophysical experiments to investigate the relationship between processing mechanisms for exocentric distance and direction. In the first experiment, the task was to discriminate exocentric distances. In the second one, the task was to discriminate exocentric directions. The individual effects of distance and direction on each task were dissociated by analyzing their corresponding psychophysical functions. Under stereoscopic-viewing conditions, distance judgments of exocentric intervals were not affected by exocentric direction. However, direction judgments were influenced by the distance between the pair of stimuli. Therefore, themechanism processing exocentric direction is dependent on exocentric distance, but the mechanism processing exocentric distance does not require exocentric direction measures. As a result, we suggest that exocentric distanceand directionare hierarchically processed, with distance preceding direction. Alternatively, and more probably, a necessary condition for processing the exocentric direction between two stimuli may be to know the location of each of them.

Effects of Stereo Viewing Conditions on Distance Perception in Virtual Environments

Several studies from different research groups investigating perception of absolute, egocentric distances in virtual environments have reported a compression of the intended size of the virtual space. One potential explanation for the compression is that inaccuracies and cue conflicts involving stereo viewing conditions in head mounted displays result in an inaccurate absolute scaling of the virtual world. We manipulate stereo viewing conditions in a head mounted display and show the effects of using both measured and fixed inter-pupilary distances, as well as bi-ocular and monocular viewing of graphics, on absolute distance judgments. Our results indicate that the amount of compression of distance judgments is unaffected by these manipulations. The equivalent performance with stereo, bi-ocular, and monocular viewing suggests that the limitations on the presentation of stereo imagery that are inherent in head mounted displays are likely not the source of distance compression reported in previous virtual environment studies.

Factors Affecting the Perception of Interobject Distances in Virtual Environments

Two experiments collectively explored four factors that may influence people's judgments of exocentric (interobject) distances in virtual environments. Participants freely navigated in a simple virtual environment and repeatedly made magnitude estimations of exocentric distances. Distances were generally overestimated. An exponential model (Stevens' power law) fit the data, and exponent estimates were generally less than unity. Geometric field of view (GFOV) and the presence of error-corrective feedback were found to have the strongest effect on accuracy. In fact, distance perception was nearly veridical when made with an 80 deg. GFOV and when receiving feedback. Display type (head-mounted versus desktop) and the presence of additional perspective cues were less influential.

Judging Perceived and Traversed Distance in Virtual Environments

The ability to accurately estimate distance is an essential component of navigating large-scale spaces. Although the factors that influence distance estimation have been a topic of research in real-world environments for decades and are well known, research on distance estimation in virtual environments (VEs) has only just begun. Initial investigations of distance estimation in VEs suggest that observers are less accurate in estimating distance in VEs than in the real world (Lampton et al., 1995). Factors influencing distance estimates may be divided into those affecting perceived distance (visual cues only) and those affecting traversed distance to include visual, cognitive, and proprioceptive cues. To assess the contribution of the various distance cues in VEs, two experiments were conducted. The first required a static observer to estimate the distance to a cylinder placed at various points along a 130-foot hallway. This experiment examined the effects of floor texture, floor pattern, and object size on distance estimates in a VE. The second experiment required a moving observer to estimate route segment distances and total route distances along four routes, each totaling 1210 feet. This experiment assessed the effects of movement method, movement speed, compensatory cues, and wall texture density. Results indicate that observers underestimate distances both in VEs and in the real world, but the underestimates are more extreme in VEs. Texture did not reliably affect the distance estimates, providing no compensation for the gross underestimates of distance in VE. Traversing a distance improves the ability to estimate that distance, but more natural means of moving via a treadmill do not necessarily improve distance estimates over traditional methods of moving in VE (e.g., using a joystick). The addition of compensatory cues (tone every 10 feet traversed on alternate route segments) improves VE distance estimation to almost perfect performance.