Shadows used to peer around corners

In non-line-of-sight imaging, the obscuring structure can block certain optical paths and cast a shadow on the relay surface (Fig. 1). The idea of using shadows in non-line-of-sight imaging was first demonstrated by turning an ordinary camera into a corner camera7, in which shadows cast by the edge of a doorway or the corner of a wall were analysed. Saunders and colleagues present an approach in which light emanating from a hidden target is partially blocked by an obscuring structure of unknown position, producing a pattern of illumination and shadow on a relay surface (Fig. 1).

Source: www.nature.com