Geodata collected and provided by volunteers (Volunteered Geographic Information), e.g. OpenStreetMap data, can show large differences in the accuracy of represented object positions. Within the framework of the DFG-funded research program, we are investigating the effects of these varying imprecisions of geodata and possibly resulting uncertainties on spatial navigation. In controlled experiments, we quantify the extent to which uncertainties of landmarks represented in maps affect orientation and navigation performance. In addition, it will be investigated whether such impairments can be counteracted by explicitly representing landmark uncertainties in maps.