Patent ID: 6608910
Filing Date: 2003-08-19
Classification: G06K

Abstract:
A computer vision apparatus for recognizing and tracking occupants in a fixed space including:at least one sensor fixedly positioned to capture light from a fixed space beginning at a time prior to an occupant's entrance and continuing subsequent to an occupant's entrance to form a series of N images having pixels with pixel intensities, the series of N images including a current image Nc and a previous image Ncâˆ’1, with the previous image Ncâˆ’1 being the image immediately prior to the current image Nc in the series of N subsequent images, the sensor converting the series of N images into electronic data; a processor positioned to receive electronic data from the sensor and to compare the current image Nc with the previous image Ncâˆ’1 in order to dynamically determine the occupant type and occupant position; computing an low-level vision-based feature map of the previous image Nc âˆ’1of the fixed space; computing an low-level vision-based feature map of the current image Nc of the fixed space; computing a residual low-level vision-based feature map having connected regions withsizes, by calculating the difference between low-level vision-based feature map of the current image Nc of the fixed space and the previous image Ncâˆ’1 of the fixed space, where the pixels corresponding to the occupant in the previous subsequent image have been replaced by corresponding pixels of the current image Nc of the fixed space; applying a high pass size filter to remove connected regions of the residual low-level vision-based feature map below a specified size, resulting in a size-filtered residual low-level-vision-based feature map including gaps and a bounded area; filling the bounded area of the size-filtered residual low-level vision-based feature map, resulting in a filled low-level vision-based feature area; calculating two-dimensional moments of the filled low-level vision-based feature area and using the two-dimensional moments to construct an equivalent rectangle with moments equal to that of the filled low-level vision-based feature area; and determining the centroid, orientation, size and aspect ratio of the equivalent rectangle.