Method and Apparatus for Projective Volume Monitoring

Abstract

According to one aspect of the teachings presented herein, a projective volume monitoring apparatus is configured to protect against the intrusion of crawling and walking persons into a monitoring zone. The apparatus acquires stereo images of a first monitoring zone that begins at a defined height above a floor and of a second monitoring zone that lies below the first monitoring zone and extends downward to a floor or other surface on which persons may walk or crawl, and processes the stereo images to obtain range pixels. The apparatus detects object intrusions within the first monitoring zone by processing the corresponding range pixels using first object detection parameters that are tuned for the detection of walking or running persons, and detects object intrusions within the second monitoring zone by processing the corresponding range pixels using second object detection parameters that are tuned for the detection of crawling or prone persons.

What is claimed is: 
     
         1 . A method of protecting against the intrusion of crawling and walking persons into a monitoring zone comprising:
 acquiring stereo images of a first monitoring zone that begins at a defined height above a floor and of a second monitoring zone that lies below the first monitoring zone and extends downward to a floor or other surface on which persons may walk or crawl;   processing the stereo images to obtain range pixels;   detecting object intrusions within the first monitoring zone by processing those range pixels corresponding to the first monitoring zone using first object detection parameters that are tuned for the detection of walking or running persons; and   detecting object intrusions within the second monitoring zone by processing those range pixels corresponding to the second monitoring zone using second object detection parameters that are tuned for the detection of crawling or prone persons.   
     
     
         2 . The method of  claim 1 , wherein the first object detection parameters include a first minimum object size threshold that defines a minimum size for detectable objects within the first monitoring zone, and further include a first maximum object speed that defines a maximum speed for detectable objects within the first monitoring zone, and wherein the second object detection parameters include a second minimum object size threshold that is larger than the first minimum object size threshold, and further include a second maximum object speed that is lower than the first maximum object speed. 
     
     
         3 . The method of  claim 1 , wherein the first monitoring zone begins about 420 mm above the floor or other surface, and wherein the second monitoring zone extends from 300 mm above the floor or other surface up to the beginning of the first monitoring zone, or up to the beginning of a defined protection zone. 
     
     
         4 . The method of  claim 2 , wherein the first minimum object size threshold is at or about 200 mm in cross section, the second minimum object size threshold is more than 200 mm in cross section, the first maximum object speed is about 1.6 m/s, and the second maximum object speed is about 0.8 m/s.