Towards Achieving Natural Visual Experience in Immersive Virtual Environments: Addressing Cybersickness and Depth Perception

Recent years have seen the virtual reality field flourish with the introduction of low cost VR devices. However, many problematics still remain such as heavy processing requirements, hardware limitations and the need for portability. Due to these, users tend to feel discomfort after long exposure to a VR device. These issues need to be addressed to achieve the full potential VR technology possesses. To this aim, this work addresses some of the perceptual issues prevalent in the modern VR technology. Visual stimuli plays an important role in how users perceive and interact with the virtual world. However, there are many discrepancies between how humans visually perceive in the real world and how they perceive in the virtual world. In VR devices, the stimuli is presented in pin-sharp focus which is different to how the stimuli is processed in the real world where humans convergence their eyes and alter their accommodation to focus on objects in the environment. To address perceptual discrepancies in VR systems, we have developed a framework that alters the visual stimuli. The system aims to introduce space-variant blurring in VR environments. The technique developed takes inspiration from the human visual system and adopts a hybrid approach to introduce multi-region foveation and depth-of-field effects into the rendering pipeline. The system can be integrated to any VR device and application. The effectiveness of the technique was validated through a user study on cybersickness. Users were exposed to a virtual environment for a fixed duration of time and the induced level of cybersickness was measured through self-assessment questionnaires and physiological signals. Overall, the system was able to reduce cybersickness levels by 66%. Other factors such as gender and age were also evaluated. Depth perception is a crucial part of how humans behave and interact with their environment. Convergence and accommodation are two important depth cues. However, when humans are immersed into the virtual environments, they experience a mismatch between these cues. This mismatch causes users to feel a discomfort while also hindering their ability to fully perceive object distances. To this aim, a user study was conducted on depth perception. The visual stimuli was altered with the developed spatial blurring technique. The study yielded a 27% improvement in user performance. Overall, the research aimed at bridging the gap between visual perception in the real world and the virtual one. The work done demonstrates how visual stimuli can be modified to allow users to achieve a more natural interaction with the virtual environment.