Reciprocal Leveling（对向水准测量）

What is reciprocal leveling? Reciprocal leveling is a surveying technique in which readings are taken from both directions between two points in order to reduce errors. In surveying, to level is to find the relative elevation of different points in the land.
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在该技术中，从两点之间的两个方向读取读数，以减少误差。在测量中，找平是指找出土地上不同点的相对高程。