An increasing number of virtual reality applications require environments that emulate real-world conditions. These environments often involve dynamic virtual humans showing realistic behaviors. Understanding user perception and navigation among these virtual agents is key for designing realistic and effective environments featuring groups of virtual humans. While collision risk significantly influences human locomotion in the real world, this risk is largely absent in virtual settings. This paper studies the impact of the expected collision feedback on user perception and interaction with virtual crowds. We examine the effectiveness of commonly used collision feedback techniques (auditory cues and tactile vibrations) as well as inducing participants to expect that a physical bump with a real person might occur, as if some virtual humans actually correspond to real persons embodied into them and sharing the same physical space. Our results indicate that the expected collision feedback significantly influences both participant behavior (encompassing global navigation and local movements) and subjective perceptions of presence and copresence. Specifically, the introduction of a perceived risk of actual collision was found to significantly impact global navigation strategies and increase the sense of presence. Auditory cues had a similar effect on global navigation and additionally enhanced the sense of copresence. In contrast, vibrotactile feedback was primarily effective in influencing local movements.

翻译：随着虚拟现实应用日益增多，对模拟真实世界环境的需求也不断增长。这类环境通常包含展现逼真行为的动态虚拟人物。理解用户在这些虚拟智能体中的感知与导航方式，是设计具有虚拟人群组的真实感与高效性环境的关键。虽然在现实世界中碰撞风险显著影响人类移动行为，但此类风险在虚拟场景中基本不存在。本文研究了预期碰撞反馈对用户感知及与虚拟人群交互的影响。我们考察了常用碰撞反馈技术（听觉提示与触觉振动）的有效性，同时引导参与者预期可能与真人发生物理碰撞——即假设部分虚拟人物实际对应着具身化于其中并共享同一物理空间的真实个体。研究结果表明，预期碰撞反馈显著影响参与者的行为（包括全局导航与局部移动）以及对存在感与共在感的主观感知。具体而言，引入实际碰撞的感知风险会显著影响全局导航策略并增强存在感；听觉提示对全局导航产生类似影响，同时还能提升共在感；相比之下，振动触觉反馈主要影响局部移动行为。