Symbol adaptation assessment in outdoor augmented reality

A challenge in presenting augmented reality information, particularly in outdoor environments, is to distinguish the virtual symbols from the background image. In this paper we report on a user study that leverages prior knowledge about adaptations to improve symbol conspicuity by expanding its application to outdoor environments and mobile handheld devices. We considered two types of adaptation that yielded good results indoors, namely adding a border around the symbol and adjusting the colour luminosity, and tested them outdoor in daylight. We also introduced partial and total adaptation modes that differed in the scope of the symbols to adapt: only the ones that are almost imperceptible from the background versus every symbol overlaying the real world image. Results from users' questionnaires reveal that the border adaptation continues to be the favourite regardless of the outdoor lighting conditions, and yet we did not find differences in symbol detection performance in comparison with adjusting colour luminosity. The border adaptation was also considered the best to preserve symbol semantics when combined with the total adaptation mode, thus making it a versatile option for augmented reality applications.