Quantifying Luning: Perceptual fading at mono-binocular boundaries in augmented reality

In near-eye display systems for augmented reality (AR), partial binocular overlap between the left and right fields of view (FOV) can arise due to factors such as the depth of virtual content, users interpupillary distance (IPD), and efforts to expand perceived FOV coverage. This partial overlap divides the FOV into three regions: a central binocular zone and two peripheral monocular zones. At the binocular-monocular (BM) borders, users may perceive a fading of virtual content, commonly known as Luning artifacts. Most prior research has measured these artifacts by the proportion of time users detected fading, which provides limited insight into the severity and spatial profile of the effect. Here, we introduce a luminance comparison paradigm to quantitatively measure perceptual fading as a function of horizontal position relative to the BM borders. Measurements conducted on AR wearables demonstrate that this method effectively quantifies the Luning artifacts and enables objective assessment of potential mitigation strategies, such as vignetting of the FOV near the nasal boundary in each eye. Additionally, our findings reveal that the spatial profile of the perceptual fading differs between the left and right BM borders, which suggests close links to users ocular dominance.