概述 Overview

      建筑物、道路等工程总是在起伏不平的地面上修建的，有时无法用三面投影图表达清楚，所以选用标高投影法来绘制地形图。

      Buildings, roads and other projects are always built on the undulating ground, and sometimes it is impossible to express clearly with three-side projection map, so elevation projection method is selected to draw.

      标高投影法采用水平投影并标注特征点、线、面的高度数值来表达空间形体，它是一种标注高度数值的单面正投影。

      Elevation projection method USES horizontal projection and mark the height value of feature points, lines and planes to express the spatial body.

      用一组等间隔的水平面截割地形曲面，得到一组水平截交线，称为等高线。将它们投射到水平投影面（基准面）上，并标出各自的标高，即得标高投影图，也称地形图。见图10-1。

      A set of horizontal intersecting lines, called contour lines, are obtained by cutting the terrain surface with a set of equal-spaced horizontal planes. Project them onto a horizontal projection plane (datum plane) and mark their respective elevations.

       

图10-1 地形图