1)Key Laboratory of Mine Spatial Information Technologies,National Administration of Surverying,
Mapping and Geoinformation,Henan Polytechnic University, Jiaozuo 454000
2)Henan Geomatics Center, Zhengzhou 450003
3)Henan Remotesensing and Mapping Institute,Zhengzhou 450003
Abstract：In the case of big inclination angle,traditional methods extracting the center of circular planar target in TLS do not work and a part of data will miss.A new algorithm based on edge fitting is proposed.The firstl step is to extract automatically edge points of circular plane target，The second step is to fitt spatial circle by edge points and determine the center of the target.Experimental results show that this algorithm is simple and feasible，the extracting accuracy is consistent with that by software in suitable conditions；In the case of big inclination angle or missing data，this algorithm can also determine accurately the coordinates of target center.
