Getting lost in the library—or any other large indoor space such as an airport, museum, or conference center—is the result of both personal and environmental factors, says geographer Rui Li. Personal factors include one's familiarity with the location and general sense of direction. Environmental factors include a building's line-of-sight visibility, differences in architectural style, and spatial complexity, or the number of possible paths to or from any one location. Geographers call this confluence of factors wayfinding.