Influence of Atmosphere Refraction on Horizontal Angle Surveying and Countermeasures

Choosing oriented direction is crucial to line-angle surveying in line-angle nets is put forward in the paper,and how to select the oriented direction as surveying the angles and the means to check the quality of auto-surveying with Georobot are brought forward as well.At last,it expounds some countermeasures to reduce the influence of side-refraction when dispose and survey ultrahigh-precision line angle nets.