Computer Engineering Department and Virtual Reality Application Center, Iowa State University, Ames, IA 50014, USA.
IEEE Trans Vis Comput Graph. 2012 Apr;18(4):581-8. doi: 10.1109/TVCG.2012.58.
Stereoscopic depth cues improve depth perception and increase immersion within virtual environments (VEs). However, improper display of these cues can distort perceived distances and directions. Consider a multi-user VE, where all users view identical stereoscopic images regardless of physical location. In this scenario, cues are typically customized for one "leader" equipped with a head-tracking device. This user stands at the center of projection (CoP) and all other users ("followers") view the scene from other locations and receive improper depth cues. This paper examines perceived depth distortion when viewing stereoscopic VEs from follower perspectives and the impact of these distortions on collaborative spatial judgments. Pairs of participants made collaborative depth judgments of virtual shapes viewed from the CoP or after displacement forward or backward. Forward and backward displacement caused perceived depth compression and expansion, respectively, with greater compression than expansion. Furthermore, distortion was less than predicted by a ray-intersection model of stereo geometry. Collaboration times were significantly longer when participants stood at different locations compared to the same location, and increased with greater perceived depth discrepancy between the two viewing locations. These findings advance our understanding of spatial distortions in multi-user VEs, and suggest a strategy for reducing distortion.
立体深度线索可改善对虚拟环境 (VE) 的深度感知并增加沉浸感。然而，这些线索的不当显示会扭曲感知的距离和方向。考虑一个多用户 VE，其中所有用户都查看相同的立体图像，无论其物理位置如何。在这种情况下，线索通常针对配备头部跟踪设备的一个“领导者”进行定制。此用户位于投影中心 (CoP)，所有其他用户（“跟随者”）从其他位置查看场景并接收不当的深度线索。本文研究了从跟随者角度观看立体 VE 时的感知深度失真以及这些失真对协作空间判断的影响。参与者成对地从 CoP 或向前或向后位移后对虚拟形状进行协作深度判断。向前和向后位移分别导致感知深度压缩和扩展，压缩比扩展大。此外，失真小于立体几何射线相交模型的预测。与处于同一位置相比，当参与者处于不同位置时，协作时间明显更长，并且当两个观察位置之间的感知深度差异更大时，协作时间会增加。这些发现增进了我们对多用户 VE 中空间失真的理解，并提出了一种减少失真的策略。
