New System to Measure Motion MotiontoPhoton Latency of Virtual Reality Head Mounted Display Head mounted display (HMD) is an important part of the virtual reality (VR) system and the main interface of virtual world. During the process of using HMD, there is a certain time gap between the useru0027s movement and the triggered change of display, which is referred to herein as a  Motionto Photon  latency. The latency may cause cybersickness which has an adverse effect on user experience and even physical health, so it is necessary to evaluate the latency of an HMD. We propose an automated and universal HMD latency measurement system. By simulating a userxe2x80x99s motion, we are able to measure MotiontoPhoton latency using the generated periodic signals in HMD, with accuracy and reliability confirmed by our experiments. The system is fully automatic and easy to use, and suitable for the HMD with insideout or outsidein positioning methods. It helps to improve both the detection level of existing HMDs and the user experience. It is of guiding significance for the design and manufacture of new HMD.

Perceptual Tolerance to MotionToPhoton Latency with Head Movement in Virtual Reality Since MotionToPhoton (MTP) latency is inevitable and can be perceived in virtual reality, quantifying perception of MTP latency becomes necessary. In this paper, we investigate perceptual tolerance to MTP latency, including perception threshold of the latency and user acceptance of delays above the threshold. It is affected by different head motion events, such as MotionStaticAlternate (MSA, i.e., an acceleration or deceleration in one direction) and MotionToReverse (MTR, i.e., a movement reverses direction). In each motion event, rotation angle and angular velocity also influence perception of MTP latency. Experimental results show that subjects are more intolerant of MTP latency in MTR than MSA. The latency perception threshold is about 23 ms when subjects turn their heads at the maximum speed of human limits. When the angular velocity decreases, the perception threshold increases. The maximum threshold is 41 ms at 20 xc2xb0s in this study. Inversely proportional models are established to describe the relationship between threshold and angular velocity. Besides, MTP latency over the threshold is harder to be accepted with the rotation angle decreasing or the angular velocity increasing.