How to visualize the spatial uncertainty of landmark representations in maps?

Landmark representations in maps play an important role in spatial tasks such as self-localization, spatial orientation, and navigation. By matching landmarks to their map representations, people can identify their current location and orientation within a map. However, spatial inaccuracies of landmark representations like these of pictograms in maps have been found to affect the ability to successfully match spatial environments to their map representations. These map matching difficulties could negatively affect the performance in spatial tasks. Due to the increasing number of data sources used in modern map services, for example provided by volunteers, map data quality has become more heterogeneous and uncertain. Therefore, solutions for counteracting the negative effects of spatially inaccurate landmark representations on map matching are required. Here, we report two studies that investigate whether visualizing spatial landmark uncertainty can improve map matching. Although suggestions for visualizing uncertainty exist, there is no empirical evidence whether they can intuitively communicate spatial uncertainty of landmark representations. If map users are made aware of potential spatial inaccuracies in a map, they may observe small or moderate spatial inaccuracies of landmark representations but still be able to match these to the represented landmarks. Our findings support this assumption. Using pictogram size, transparency, or circular uncertainty areas around pictograms to communicate spatial uncertainty increased the likelihood of a perceived match between 3D environments or 360° images and a corresponding map representation when landmark representations were spatially inaccurate. Furthermore, our findings indicate that, in addition to landmarks, people use spatial reference points such as road segments for map matching. Thus, if sufficient other spatial reference points are available both in the environment and its map representation, negative effects of spatially inaccurate landmark representations on map matching may be less severe.