1. A method for 3D imaging of an occupant in a motor vehicle for vehicle occupancy determination, the method comprising: projecting an illumination light source onto a motor vehicle intended to be analyzed for vehicle occupancy determination, said illumination source comprising structured light in the Short Wave Infrared (SWIR), said structured light being projected through an optical element comprising a patterned grid, a reflection of said source light being sensed by an imaging sensor; shifting said sensed reflected source light to a wavelength range of a CCD device, said wavelength-shifted light being an image in a structured pattern; using an infrared detector operating in the near infrared range of 700-1000 nm to detect said wavelength-shifted light; for each pixel in said structured patterned image: analyzing said detected wavelength-shifted light to determine an amount of distortion caused by 3D surface variation at this pixel location; and converting said distortion to a depth value for this pixel; constructing a 3D image using each pixel's respective depth value; and determining a number of occupants in said vehicle by analyzing said 3D image.