A display controlling method, applied to a display, comprising: (a) applying a target apparatus to capture an image to be compared; (b) comparing image content of the image to be compared and image content of a reference image to generate image relation information; (c) determining a relative location between the target apparatus and the display according to the image relation information; and (d) controlling the display to display an image according to the relative location. The steps (a), (b) and (c) can constitute a relative location determining method. The present invention also discloses systems applying the methods.