The Effects of Visual Behavior and Ego-Movement on Foveated Rendering Performance in Virtual Reality

Despite the recent developments in VR, maintaining photorealism is difficult due to the increased bandwidth capabilities and computational resources required. To make VR more affordable, techniques such as Foveated Rendering (FR) offer promising ways to optimise rendering without compromising the user experience. Near-eye displays with 6DOF tracking enable users to freely move through the environment. This was previously impossible with traditional displays. This work aims to disentangle the effect of type of ego-movement (Active versus Implied) and task type (Simple Fixations versus a task involving Fixations, Discrimination, and Counting) on a dynamic FR method developed using Variable Rate Shading (VRS) (a quarter of the native shading rate is used in the visual periphery). We also explore if the aforementioned effects are consistent under different visual behaviours (visual search versus tracking). Results show that participants actively moving and performing complex tasks (during visual search) are less sensitive to degradation than in other conditions, with only 31.7% of the FOV required to be rendered using full sampling. Additionally, we provide evidence for how instances of visual pursuit might influence these results; in this case, only 29.3% of the FOV rendered using full sampling is tolerated by participants.