Patent ID: 8669876

Claim:
A system for monitoring swimming pools for possible drowning victims, the system comprising: a) a passive sensor, positioned above a surface of a pool, the sensor comprising means for receiving an image of an object located at or below the surface of the pool, b) means for digitizing images received from the sensor, c) a programmable computer connected to receive data from the digitizing means, the computer being programmed to analyze the images to determine whether the images indicate a presence of a drowning victim in the pool, and d) means for alerting an operator of the presence of a drowning victim, wherein the computer comprises entirely passive means for compensating for refraction of images caused by a roughened water surface due to surface waves in the pool, wherein the water surface defines a plurality of areas having different refraction properties, wherein the computer comprises: e) a spectral processor for decomposing each image into principal components, f) a spatial processor which receives input from the spectral processor, the spatial processor comprising means for detecting predetermined shapes in the images, and g) a temporal processor which receives input from the spatial processor, the temporal processor comprising means for analyzing sequences of images and for detecting the presence of predetermined movements of said predetermined shapes in said sequences of images, wherein said predetermined shapes comprise human forms, and wherein said predetermined movements comprise vertical movements and vertical movements with rotation.