1. A method for multi-mode video event indexing, the method comprising: applying background subtraction to images from a video stream input to detect foreground object activity as a difference between current frame image information and static information of a contextual background of the video stream input images; measuring an amount of light intensity within the video stream input images; in response to the measured amount of light intensity meeting a threshold illumination level value, a processor selecting an object tracking based analytic mode from a plurality of video analytics modes and applying the object tracking based analytic mode to remove shadow pixels from regions of the detected foreground object activity of the video stream input images and to track remaining pixels of the detected foreground object activity within the video stream input images; and in response to the measured amount of light intensity not meeting the threshold illumination level value, the processor selecting a non-object tracking based analytic mode from the plurality of video analytics modes and applying the non-object tracking based analytic mode to the detected foreground object activity of the video stream input images, wherein applying the non-object tracking based analytic mode comprises: defining a virtual boundary line of a region of interest within the video input images; establishing a plurality of overlapping ground patch regions along each side of the virtual boundary line; analyzing in real-time each of the ground patch regions in the video input images data to identify attributes of objects detected in the region of interest; and determining current appearance features of foreground objects identified within the region of interest; and wherein the non-object tracking based analytic mode is different from the object tracking based analytic mode and parses video events from the detected foreground object activity of the video stream images for object activity detection without removing shadow pixels from the regions of the detected foreground object activity.