Natural surveillance depends on the spatial configuration creating a strong probabilistic interface between inhabitants and strangers in space that is the source of safety. The natural movement of moving strangers is said to provide natural surveillance on space, while the static inhabitants, through their dwelling entrances and windows, maintain natural surveillance of moving strangers.
Hillier, B., Turner, A., Yang, T., Park, H-T. (2007, 2010) Metric and topo-geometric properties of urban street networks: some convergencies, divergencies and new results. The Journal of Space Syntax, V(1) 2, 258-279.pp. 146