The Influence of Environmental Lighting on Size Variations in Optical See-through Tangible Augmented Reality

Optical see-through head-mounted displays (OST HMDs) are becoming increasingly popular as they get better and smaller. One application area is interaction with virtual content, which is more intuitive when using physical objects as tangibles. Since it is not possible to use a matching replica for each virtual object, it is necessary to identify physical objects that can represent several different virtual objects. As a first step, we investigated to what extent a physical object can differ in size from its virtual counterpart. Since the perception of content in optical see-through Augmented Reality (OST AR) is strongly influenced by the ambient lighting, the illumination intensity was considered in our study. We investigated three indoor lighting conditions and their effects on the perception of seven different size variations between the physical object and its virtual overlay. The results of the study show that there is a decrease in usability and presence with increasing illuminance. However, this cannot be avoided when applications are run under realistic interior lighting conditions. Furthermore, the results demonstrate that the size ranges in which a physical object can deviate from its virtual counterpart without having a strong negative impact on usability, presence and performance increase with increasing environmental illumination. Therefore, it is possible to interact with even smaller and even larger physical props to manipulate the associated virtual content under brighter lighting conditions.