A depth sensing based system comprising: a depth sensor for detecting a number of occupants in a site; and an occupancy identification module coupled to the depth sensor and is configured to perform at least one of verifying, tracking or identifying the number of occupants entering and existing the site, wherein the occupancy identification module is configured to: verify whether the occupant is a human ; track the occupant is either entering or existing the site; and identify at least one of head radius, shoulder size, height, walking speed of the occupant, wherein the depth sensing based system further comprising a depth estimation module configured to scan various depth levels of the occupant and extract contours of a head of the occupant, and further configured to verify the presence of a head and to verify the presence of a shoulder by using an orientation invariant 3D human model, wherein in order to verify the presence of the shoulder, a region of interest , ROI, surrounding the head and the shoulder is considered, and wherein the depth sensing based system is further configured to detect a location of one door and to determine whether the occupant is entering or leaving the site for estimating the number of occupants at the site. a depth sensor for detecting a number of occupants in a site; and an occupancy identification module coupled to the depth sensor and is configured to perform at least one of verifying, tracking or identifying the number of occupants entering and existing the site, wherein the occupancy identification module is configured to: verify whether the occupant is a human ; track the occupant is either entering or existing the site; and identify at least one of head radius, shoulder size, height, walking speed of the occupant, wherein the depth sensing based system further comprising a depth estimation module configured to scan various depth levels of the occupant and extract contours of a head of the occupant, and further configured to verify the presence of a head and to verify the presence of a shoulder by using an orientation invariant 3D human model, wherein in order to verify the presence of the shoulder, a region of interest , ROI, surrounding the head and the shoulder is considered, and wherein the depth sensing based system is further configured to detect a location of one door and to determine whether the occupant is entering or leaving the site for estimating the number of occupants at the site. verify whether the occupant is a human ; track the occupant is either entering or existing the site; and identify at least one of head radius, shoulder size, height, walking speed of the occupant, wherein the depth sensing based system further comprising a depth estimation module configured to scan various depth levels of the occupant and extract contours of a head of the occupant, and further configured to verify the presence of a head and to verify the presence of a shoulder by using an orientation invariant 3D human model, wherein in order to verify the presence of the shoulder, a region of interest , ROI, surrounding the head and the shoulder is considered, and wherein the depth sensing based system is further configured to detect a location of one door and to determine whether the occupant is entering or leaving the site for estimating the number of occupants at the site. <EOS>