The location of cities , roads , and political boundaries that exist on the surface of the earth are projected onto a two - dimensional display or piece of paper , preserving the relative positions and relative distances of the rendered objects 實(shí)際的城市,道路,及行政區(qū)劃邊界被投影為二維的圖形,保留了原來(lái)的相對(duì)位置及相對(duì)距離,并可進(jìn)行顯示或打印。