**3.3 Structured light RGB-D sensor**

Depth sensors based on structured light (SLS) need additive light source. This source projects the regular patterns to the scene. The surface of the object distorts this regular pattern. If the structure of light pattern is known, the depth image of the scene can be easily computed based on its distortion [23]. Light patterns are emitted in infrared band, so the entire process is invisible to the user. If stripes are used as regular patterns, the optical resolution of the depth map can be increased by the reduction of strips width.
