Method and Apparatus for Projective Volume Monitoring

A projective volume monitoring apparatus configured to detect objects intruding into a monitoring zone, said projective volume monitoring apparatus comprising:

• image sensors configured to capture a stereo image;
• and
• image processing circuits operatively associated with the image sensors and configured to:
• correlate the stereo image to obtain a depth map comprising pixels represented in three-dimensional Cartesian coordinates;
• convert the range pixels into spherical coordinates, so that each range pixel is represented as a radial distance along a respective pixel ray and a corresponding pair of solid angle values within the horizontal and vertical fields of view associated with capturing the stereo image;
• obtain a set of flagged pixels by flagging those range pixels that fall within a protection boundary defined for the monitoring zone;
• accumulate the flagged pixels into corresponding cells of a two-dimensional histogram that quantizes the solid angle ranges of the horizontal and vertical fields of view;
• and
• cluster cells in the histogram to detect intrusions of objects within the protection boundary that meet a minimum object size threshold.

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.