Locomotion is a fundamental interaction element allowing navigation inside the virtual environment, and the walking-in-place (WIP) techniques have been actively developed as a balanced compromise between naturalness and efficiency. One popular method to implement the WIP technique was to use a low-cost, easy to set up, and markerless Kinect, but required integration of multiple sensors or covered limited directions due to the poor tracking capability when facing non-frontal sides of the user. This study aimed to propose a WIP technique for omnidirectional VR locomotion based on a single RGB camera, utilizing an open-source 2D human pose estimation system called OpenPose. Three WIP techniques (existing Kinect-based technique, proposed Kinect-based technique, and proposed OpenPose-based technique) were compared in terms of variation of virtual walking speed and subjective evaluation through a user study with walking tasks in different directions. Experimental results showed that the proposed OpenPose-based technique performed comparably when the user faced the front of the camera, but it induced lower variation of virtual walking speed and higher subjective evaluation ratings at non-forward directions compared to other techniques. The proposed OpenPose-based WIP technique can be used in VR applications to provide a fully unobstructed VR locomotion experience. It can achieve stable WIP-based omnidirectional VR locomotion through a single low-cost easily accessible RGB camera, without the need for additional sensors, and at the same time, both hands are free for other interactions.

运动是允许在虚拟环境中导航的基本交互元素，并且原地行走 (WIP) 技术已被积极开发，作为自然性和效率之间的平衡折衷。实现 WIP 技术的一种流行方法是使用低成本、易于设置且无标记的 Kinect，但由于面对用户的非正面时跟踪能力较差，因此需要集成多个传感器或覆盖有限的方向. 本研究旨在提出一种基于单个 RGB 摄像头的全向 VR 运动 WIP 技术，利用名为 OpenPose 的开源 2D 人体姿态估计系统。三种 WIP 技术（现有的基于 Kinect 的技术，提出的基于 Kinect 的技术，和提出的基于 OpenPose 的技术）在虚拟步行速度的变化和主观评价方面进行了比较，通过用户研究和不同方向的步行任务。实验结果表明，当用户面对相机正面时，所提出的基于 OpenPose 的技术表现相当，但与其他技术相比，它在非向前方向上引起了较低的虚拟步行速度变化和较高的主观评价评级。提议的基于 OpenPose 的 WIP 技术可用于 VR 应用程序，以提供完全畅通无阻的 VR 运动体验。它可以通过单个低成本、易于访问的 RGB 摄像头实现稳定的基于 WIP 的全方位 VR 运动，无需额外的传感器，同时双手可以自由进行其他交互。