The Effect of Anthropometric Properties of Self-Avatars on Action Capabilities in Virtual Reality

The field of Virtual Reality (VR) has seen a steady exponential uptake in the last decade and is being continuously incorporated into areas of popular interest like healthcare, training, recreation and gaming. This steady upward trend and prolonged popularity has resulted in numerous extravagant virtual environments, some that aim to mimic real-life experiences like combat training, while others intend to provide unique experiences that may otherwise be difficult to recreate like flying over ancient Egypt as a bird. These experiences often showcase highly realistic graphics, intuitive interactions and unique avatar embodiment scenarios with the help of various tracking sensors, high definition graphic displays, sound systems, etc. The literature suggests that estimates and affordance judgments in VR scenarios such as the ones described above are affected by the properties and the nature of the avatar embodied by the user. Therefore, to provide users with the finest experiences it is crucial to understand the interaction between the embodied self and the action capabilities afforded by it in the surrounding virtual environment. In a series of studies aimed at exploring the effect of gender matched body-scaled self-avatars on the user\u27s perception, we investigate the effect of self-avatars on the perception of size of objects in an immersive virtual environment (IVE) and how this perception affects the actions one can perform as compared to the real world. In the process, we make use of newer tracking technology and graphic displays to investigate the perceived differences between real world environments and their virtual counterparts to understand how the spatial properties of the environment and the embodied self-avatars affect affordances by means of passability judgments. We describe techniques for creation and mapping VR environments onto their real world counterparts and the creation of gender matched body-scaled self-avatars that provides real time full-body tracking. The first two studies investigate how newer graphical displays and off-the-shelf tracking devices can be utilized to create salient gender matched body-scaled self-avatars and their effect on the judgment of passability as a result of the embodied body schema. The study involves creating complex scripts that automate the process of mapping virtual worlds onto their real world counterparts within a 1cm margin of error and the creation of self-avatars that match height, limb proportions and shoulder width of the participant using tracking sensors. The experiment involves making judgments about the passability of an adjustable doorway in the real world and in a virtual to-scale replica of the real world environment. The results demonstrated that the perception of affordances in IVEs is comparable to the real world but the behavior leading to it differs in VR. Also, the body-scaled self-avatars generated provide salient information yielding performance similar to the real world. Several insights and guidelines related to creating veridical virtual environments and realistic self-avatars were achieved from this effort. The third study investigates how the presence of body-scaled self-avatars affects the perception of size of virtual handheld objects and the influence of the person-plus-virtual-object system created by lifting the said virtual object on passability. This is crucial to understand as VR simulations now often utilize self-avatars that carry objects while maneuvering through the environment. How they interact with these handheld objects can influence what they do in critical scenarios where split second decisions can change the outcome like combat training, role-playing games, first person shooting, thrilling rides, physiotherapy, etc. It has also been reported that the avatar itself can influence the perception of size of virtual objects, in turn influencing action capabilities. There is ample research on different interaction techniques to manipulate objects in a virtual world but the question about how the objects affect our action capabilities upon interaction remains unanswered, especially when the haptic feedback associated with holding a real object is mismatched or missing. The study investigates this phenomenon by having participants interact with virtual objects of different sizes and making frontal and lateral passability judgments to an adjustable aperture similar to the first experiment. The results suggest that the presence of self-avatars significantly affects affordance judgments. Interestingly, frontal and lateral judgments in IVEs seem to similar unlike the real world. Investigating the concept of embodied body schema and its influence on action-capabilities further, the fourth study looks at how embodying self-avatars that may vary slightly from your real world body affect performance and behavior in dynamic affordance scenarios. In this particular study, we change the eye height of the participants in the presence or absence of self-avatars that are either bigger, smaller or the same size as the participant. We then investigate how this change in eye height and anthropometric properties of the self-avatar affects their judgments when crossing streets with oncoming traffic in virtual reality. We also evaluate any changes in the perceived walking speed as a result of embodying altered self-avatars. The findings suggest that the presence of self-avatars results in safer crossing behavior, however scaling the eye height or the avatar does not seem to affect the perceived walking speed. A detailed discussion on all the findings can be found in the manuscript

I Look Great! Beautified Self-Avatars\u27 Effects on Willingness-To-Pay in Metaverses

This study represents ongoing research to investigate the impact of self-avatar beautification on consumers’ willingness to pay for products virtually tried on with a beautified avatar. Avatars are the primary means of representing users in the rapidly growing market for commercial metaverse applications, such as apparel and accessories try-on. Based on self-congruity theory and appraisal theory, we argue that beautified self-avatars are congruent with users\u27 ideal selves and elicit identification and positive emotions, resulting in increased willingness to pay. We present preliminary findings that support the notion that beautified avatars promote the ideal self and result in greater willingness to pay than realistic avatars. With these findings we contribute to research on avatar design and commerce in metaverses, by challenging the recognised notion that self-avatars should be as realistic as possible and establishing avatar beautification as a novel design objective in metaverse marketing

Beauty is in the Eye of the Controller: Designing Avatars for the Actual and Ideal Self

As metaverses are growing users need self-avatars to complete more and more tasks, such as virtual clothing-try-on or virtual work-meetings. To design these self-avatars the application of self-congruity theory suggests that avatars\u27 appearance should ei-her be congruent with users’ actual view of themselves or ideal view of themselves. Past research has focused on comparing outcomes of using idealised avatars versus realistic avatars. Yet, it remains unclear what constitutes the ideal versus the actual self in avatar design. This short paper represents ongoing research to develop a theoretical avatar design framework to evoke either users\u27 ideal or actual self. Building on evolutionary and computational approaches to facial beauty, we identify three groups of design factors that stimulate the ideal self: skin-homogeneity, face-symmetry, and balanced face-ratios. This work advances our understanding of the antecedents of the ideal versus actual self and makes self-congruity theory applicable to avatar design

Fitted avatars: automatic skeleton adjustment for self-avatars in virtual reality

In the era of the metaverse, self-avatars are gaining popularity, as they can enhance presence and provide embodiment when a user is immersed in Virtual Reality. They are also very important in collaborative Virtual Reality to improve communication through gestures. Whether we are using a complex motion capture solution or a few trackers with inverse kinematics (IK), it is essential to have a good match in size between the avatar and the user, as otherwise mismatches in self-avatar posture could be noticeable for the user. To achieve such a correct match in dimensions, a manual process is often required, with the need for a second person to take measurements of body limbs and introduce them into the system. This process can be time-consuming, and prone to errors. In this paper, we propose an automatic measuring method that simply requires the user to do a small set of exercises while wearing a Head-Mounted Display (HMD), two hand controllers, and three trackers. Our work provides an affordable and quick method to automatically extract user measurements and adjust the virtual humanoid skeleton to the exact dimensions. Our results show that our method can reduce the misalignment produced by the IK system when compared to other solutions that simply apply a uniform scaling to an avatar based on the height of the HMD, and make assumptions about the locations of joints with respect to the trackers.This work was funded by the Spanish Ministry of Science and Innovation (PID2021-122136OB-C21). Jose Luis Ponton was also funded by the Spanish Ministry of Universities (FPU21/01927).Peer ReviewedPostprint (published version

Virtualna bolnica

Smart hospital is a relatively familiar concept, and it has become a reality. In this paper, we go a step further and problematize the virtual hospital. The aim of the paper is to show that the virtual hospital is achievable and has its own purpose. The hypothesis is that the virtual hospital helps to improve healthcare. The methods used in the investigation are the study of literature, analysis of the same, as well as analysis of concepts like avatar, Internet of Things (IoT), Big Data and Digital Twins. The expected results of this research will show that creating a virtual hospital is possible and that it helps in providing better healthcare.Pametna bolnica je relativno poznat koncept koji danas već postaje stvarnost. U ovom radu idemo korak dalje i problematiziramo virtualnu bolnicu. Cilj rada je pokazati da je virtualna bolnica ostvariva i da ima svoju svrhu. Hipoteza je da virtualna bolnica može pomoći u poboljšanju zdravstvene skrbi. Metode primijenjene u razmatranjima navedene hipoteze su proučavanje literature, analiza iste, te analiza koncepata poput avatara, Internet of Things (IoT), Big Data i Digital Twins. Očekivani rezultati istraživanja pokazuju da je stvaranje virtualne bolnice moguće i da pomaže u pružanju bolje zdravstvene zaštite

How Foot Tracking Matters: The Impact of an Animated Self-Avatar on Interaction, Embodiment and Presence in Shared Virtual Environments

The use of a self-avatar representation in head-mounted displays has been shown to have important effects on user behavior. However, relatively few studies focus on feet and legs. We implemented a shared virtual reality for consumer virtual reality systems where each user could be represented by a gender-matched self-avatar controlled by multiple trackers. The self-avatar allowed users to see their feet, legs and part of their torso when they looked down. We implemented an experiment where participants worked together to solve jigsaw puzzles. Participants experienced either no-avatar, a self-avatar with floating feet, or a self-avatar with tracked feet, in a between-subjects manipulation. First, we found that participants could solve the puzzle more quickly with self-avatars than without self-avatars; but there was no significant difference between the latter two conditions, solely on task completion time. Second, we found participants with tracked feet placed their feet statistically significantly closer to obstacles than participants with floating feet, whereas participants who did not have a self-avatar usually ignored obstacles. Our post-experience questionnaire results confirmed that the use of a self-avatar has important effects on presence and interaction. Together the results show that although the impact of animated legs might be subtle, it does change how users behave around obstacles. This could have important implications for the design of virtual spaces for applications such as training or behavioral analysis

Animation Fidelity in Self-Avatars: Impact on User Performance and Sense of Agency

The use of self-avatars is gaining popularity thanks to affordable VR headsets. Unfortunately, mainstream VR devices often use a small number of trackers and provide low-accuracy animations. Previous studies have shown that the Sense of Embodiment, and in particular the Sense of Agency, depends on the extent to which the avatar's movements mimic the user's movements. However, few works study such effect for tasks requiring a precise interaction with the environment, i.e., tasks that require accurate manipulation, precise foot stepping, or correct body poses. In these cases, users are likely to notice inconsistencies between their self-avatars and their actual pose. In this paper, we study the impact of the animation fidelity of the user avatar on a variety of tasks that focus on arm movement, leg movement and body posture. We compare three different animation techniques: two of them using Inverse Kinematics to reconstruct the pose from sparse input (6 trackers), and a third one using a professional motion capture system with 17 inertial sensors. We evaluate these animation techniques both quantitatively (completion time, unintentional collisions, pose accuracy) and qualitatively (Sense of Embodiment). Our results show that the animation quality affects the Sense of Embodiment. Inertial-based MoCap performs significantly better in mimicking body poses. Surprisingly, IK-based solutions using fewer sensors outperformed MoCap in tasks requiring accurate positioning, which we attribute to the higher latency and the positional drift that causes errors at the end-effectors, which are more noticeable in contact areas such as the feet.Comment: Accepted in IEEE VR 202

Animation fidelity in self-avatars: impact on user performance and sense of agency

The use of self-avatars is gaining popularity thanks to affordable VR headsets. Unfortunately, mainstream VR devices often use a small number of trackers and provide low-accuracy animations. Previous studies have shown that the Sense of Embodiment, and in particular the Sense of Agency, depends on the extent to which the avatar's movements mimic the user's movements. However, few works study such effect for tasks requiring a precise interaction with the environment, i.e., tasks that require accurate manipulation, precise foot stepping, or correct body poses. In these cases, users are likely to notice inconsistencies between their self-avatars and their actual pose. In this paper, we study the impact of the animation fidelity of the user avatar on a variety of tasks that focus on arm movement, leg movement and body posture. We compare three different animation techniques: two of them using Inverse Kinematics to reconstruct the pose from sparse input (6 trackers), and a third one using a professional motion capture system with 17 inertial sensors. We evaluate these animation techniques both quantitatively (completion time, unintentional collisions, pose accuracy) and qualitatively (Sense of Embodiment). Our results show that the animation quality affects the Sense of Embodiment. Inertial-based MoCap performs significantly better in mimicking body poses. Surprisingly, IK-based solutions using fewer sensors outperformed MoCap in tasks requiring accurate positioning, which we attribute to the higher latency and the positional drift that causes errors at the end-effectors, which are more noticeable in contact areas such as the feet.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 860768 (CLIPE project) and from MCIN/AEI/10.13039/501100011033/FEDER, UE (PID2021-122136OB-C21). Jose Luis Ponton was also funded by the Spanish Ministry of Universities (FPU21/01927).Peer ReviewedPostprint (author's final draft

Combining motion matching and orientation prediction to animate avatars for consumer-grade VR devices

The animation of user avatars plays a crucial role in conveying their pose, gestures, and relative distances to virtual objects or other users. Self-avatar animation in immersive VR helps improve the user experience and provides a Sense of Embodiment. However, consumer-grade VR devices typically include at most three trackers, one at the Head Mounted Display (HMD), and two at the handheld VR controllers. Since the problem of reconstructing the user pose from such sparse data is ill-defined, especially for the lower body, the approach adopted by most VR games consists of assuming the body orientation matches that of the HMD, and applying animation blending and time-warping from a reduced set of animations. Unfortunately, this approach produces noticeable mismatches between user and avatar movements. In this work we present a new approach to animate user avatars that is suitable for current mainstream VR devices. First, we use a neural network to estimate the user's body orientation based on the tracking information from the HMD and the hand controllers. Then we use this orientation together with the velocity and rotation of the HMD to build a feature vector that feeds a Motion Matching algorithm. We built a MoCap database with animations of VR users wearing a HMD and used it to test our approach on both self-avatars and other users’ avatars. Our results show that our system can provide a large variety of lower body animations while correctly matching the user orientation, which in turn allows us to represent not only forward movements but also stepping in any direction.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 860768 (CLIPE project) and the Spanish Ministry of Science and Innovation (PID2021-122136OB-C21).Peer ReviewedPostprint (published version