Patent US 5,657,003

A structure movement monitoring and emergency alarm system is disclosed utilizing a convention surveyor's laser transit. The transit is leveled and positioned to "shoot" across a structure that requires emergency monitoring, such as a building wall. The vertical reference position being established by the light beam, a video camera system is utilized to maintain a real-time image of the monitored area through the telescope of the transit. Using a computer for comparing, monitoring, and alarming, this visual image is digitized and referenced with a comparison grid. At regular intervals, a new visual image is compared to the reference grid to determine the location of the structure, as well as any relative movement from the reference position. Audio and visual alarms can then be activated immediately upon the determination that the position of the monitored structure has changed past acceptable limits.