The Impact of Black Edge Artifact on QoE of the FOV-Based Cloud VR Services

Cloud virtual reality (Cloud VR) services usually introduce high latency in rendering and streaming, resulting in a mismatch between the visual and vestibular systems, causing user sickness and dizziness during the service. To solve this problem, asynchronous rendering technology is usually used to provide smooth viewing. The asynchronous solution, on the other hand, will introduce another "black edge" (BE) artifact in the service, which frequently appears at the viewport's boundary with a black area when users turn their heads. This unwanted BE artifact also has an impact on the user's quality of experience (QoE). In this paper, we investigated the impact of the BE artifact on the user's QoE of the field of view (FOV) Cloud VR gaming services. The appearance of the BE artifact during the playing period was regarded as a series of BE events and the impact of BE artifact on the users' QoE was evaluated by accumulating the influence of the BE events during the whole playing period. More specifically, the user's QoE affected by a single BE event was first evaluated by combining the area ratio and duration of the BE artifact. Then, the QoE affected by multiple BE events was analyzed, where the cumulative influence of the previous BE events on the user's current QoE was evaluated. Finally, a unified event-based evaluation model was proposed to predict the user's time-varying QoE at any point in time. Experimental results showed that the proposed model performed exceptionally well in predicting the impact of BE artifact on the user's QoE.