The gaze behavior of virtual avatars is critical to social presence and perceived eye contact during social interactions in Virtual Reality. Virtual Reality headsets are being designed with integrated eye tracking to enable compelling virtual social interactions. This paper shows that the near infra-red cameras used in eye tracking capture eye images that contain iris patterns of the user. Because iris patterns are a gold standard biometric, the current technology places the user's biometric identity at risk. Our first contribution is an optical defocus based hardware solution to remove the iris biometric from the stream of eye tracking images. We characterize the performance of this solution with different internal parameters. Our second contribution is a psychophysical experiment with a same-different task that investigates the sensitivity of users to a virtual avatar's eye movements when this solution is applied. By deriving detection threshold values, our findings provide a range of defocus parameters where the change in eye movements would go unnoticed in a conversational setting. Our third contribution is a perceptual study to determine the impact of defocus parameters on the perceived eye contact, attentiveness, naturalness, and truthfulness of the avatar. Thus, if a user wishes to protect their iris biometric, our approach provides a solution that balances biometric protection while preventing their conversation partner from perceiving a difference in the user's virtual avatar. This work is the first to develop secure eye tracking configurations for VR/AR/XR applications and motivates future work in the area.

中文翻译：

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社交虚拟头像的虹膜身份验证和眼睛动画的安全性与实用性权衡


虚拟化身的注视行为对于虚拟现实中社交互动期间的社交存在和感知眼神接触至关重要。虚拟现实耳机的设计集成了眼动追踪功能，可实现引人入胜的虚拟社交互动。本文表明，用于眼动追踪的近红外摄像头可捕获包含用户虹膜图案的眼部图像。由于虹膜图案是生物识别的黄金标准，当前的技术使用户的生物识别身份面临风险。我们的第一个贡献是基于光学散焦的硬件解决方案，用于从眼睛跟踪图像流中删除虹膜生物特征。我们用不同的内部参数来表征该解决方案的性能。我们的第二个贡献是一项具有相同不同任务的心理物理学实验，该实验研究应用此解决方案时用户对虚拟化身眼球运动的敏感性。通过推导检测阈值，我们的研究结果提供了一系列散焦参数，其中眼球运动的变化在对话环境中不会被注意到。我们的第三个贡献是一项感知研究，以确定散焦参数对感知的眼神接触、注意力、自然度和化身真实性的影响。因此，如果用户希望保护他们的虹膜生物识别，我们的方法提供了一种解决方案，可以平衡生物识别保护，同时防止他们的对话伙伴感知到用户虚拟化身的差异。这项工作是第一个为 VR/AR/XR 应用开发安全眼动追踪配置的工作，并激励了该领域的未来工作。