Method and system for monitoring an enclosure

An optical receiver picks up reflected light from an area to be monitored. Using a corresponding optical receiving signal determines an up-to-date shape for a reflected line grating, which is compared with a previously determined line grating shape acting as a reference shape. An Independent claim is also included for a motor vehicle interior inspection/monitoring system with a three-dimensional/charge coupled device (CCD) camera and/or complimentary metal oxide semiconductor (CMOS) camera.