Authors:
(1) Rafael Kuffner dos Anjos;
(2) Joao Madeiras Pereira.
Table of Links
Abstract and 1 Introduction
2 Related Work and 2.1 Virtual avatars
2.2 Point cloud visualization
3 Test Design and 3.1 Setup
3.2 User Representations
3.3 Methodology
3.4 Virtual Environment and 3.5 Tasks Description
3.6 Questionnaires and 3.7 Participants
4 Results and Discussion, and 4.1 User preferences
4.2 Task performance
4.3 Discussion
5 Conclusions and References
5 CONCLUSIONS
The use of Head-Mounted Displays occludes the user’s self, causing a decrease in the feeling of presence on the Virtual Reality session.A way of overcoming this problem is by using self-embodied avatars which improve presence and overall distance estimation in VR setups. Some factors that could influence the sense of embodiment are the realism and perspective which the avatar is viewed (in First or Third-Person Perspective). The realism of avatars are affected by the Uncanny Valley which also influence self-embodied avatars. Even though, the effects of both realism and perspective are not yet fully adressed in the literature when it comes to selfembodied avatars. For that we used three different representations varying its realism in both perspectives (1PP and 3PP) following the Uncanny Valley effect, varying from an Abstract to a Realistic Representation. For the Realistic representation we used a Point-Cloud Avatar, which uses affordable depth-sensors to map real users’ information into a user augmented-self inside the Virtual Environment. To assess each of the representation-perspective combinations, we chose natural tasks such as walking while avoiding obstacles and catching thrown objects.
As a result of the statistical analysis, discussion and evaluation of the results, we propose the following guidelines regarding body representation and camera perspective for embodied virtual reality applications:
• The uncanny valley effect is more prevalent on the third person perspective, and it influences the time efficiency of navigation tasks.
• On a First-Person Perspective (1PP), the Uncanny Valley Effect is only noticed on tasks where a higher sense of embodiment is required (eg. reflex-based tasks).
• To avoid the Uncanny Valley Effect, one should use either a simplified (Abstract) or a Realistic (Point-Cloud) representation of the participant.
• Using a more realistic representation (Point-Cloud) and Perspective (1PP) can lead to faster execution times, but lower efficacy on the execution of tasks.
• A Third-Person Perspective is recommended when spatial awareness on the horizontal navigation plane is required, with a slight advantage when using a Realistic Representation.
• Obstacle avoidance and reaching moving objects can be problematic when using a Realistic representation due to occlusions created by the visually richer representation.
• The users’ sense of balance is negatively affected by a ThirdPerson Perspective.
• Reflex-based tasks have better performance when using a First-Person Perspective.
However, we were not able to clarify certain aspects investigated in this study. Namely, avoiding obstacles in the vertical plane, and how the poor estimation of distance can influence these tasks, and if the body representation has any effect on this matter. Also, the effect of the Uncanny Valley on reflex-based tasks was noticed, but requires further evaluation using different stimuli.
Going forward, different tasks should be considered for the same perspectives and avatars, such as collaboration between different users, social environments, and communicative tasks.
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