A control circuit and a method for charge sharing are provided. A straight line synthetic background is calculated directly from the measurement curve on the basis of initial and end values of the characteristic spectral peak, and the peak is integrated over the straight line, or a maximum height of the peak over the straight line, or another characteristic value of the peak relative to the straight line is utilized. A range finder is then used to measure the range to a plurality of points within the target area to allow a three dimensional image to be recreated. The soft inner layer comprises a plurality of impact absorbing units. A canopy substantially surrounds the first frame.