(一) 正弦繪角法——黄河流域的地形测量,現均採用经纬儀视距测绘法。地形测量隊由三角班(或导線班)、水平班、地形班组成。地形支导線由地形放施测,施测支导線时,同时进行测量地形支导線,每一测站用三稜尺、膠质分度器隨测随绘。绘地形支导線所用之膠质分度器的最小分划为半度(即30分),但在实际测量时前旗所选之不測站,絕大部分不是恰在速度或半度線上,在出支导線 (A) Sine draw angle method - the terrain measurement of the Yellow River Basin, are now using theodolite line of sight mapping method. Topographic survey team consists of triangular classes (or wire classes), level classes, terrain classes. Topography branch line is measured by topography. When measuring branch leads, the terrain branch wires are measured at the same time. Each station is measured with three prism ruler and gel indexer. The minimum division of the gel indexer used to paint the terrain support line is a half degree (ie 30 points), but most of the unintended stations selected by the front flag in the actual survey are not just on the speed or half line Out of support lines