Target Instrument And Surveying System

A surveying system comprises a laser scanner for scanning a distance measuring light and for acquiring point cloud data and a target instrument having a target for reflecting the distance measuring light, wherein the target is a sphere having a known diameter, the laser scanner comprises a distance measuring module for projecting the distance measuring light, for receiving a reflected distance measuring light and for performing a distance measurement, an optical axis deflector which enables to two-dimensionally deflect the distance measuring light, and an arithmetic control module for controlling the optical axis deflector, and wherein the arithmetic control module is configured to perform a circular scan on a surface of the target by the optical axis deflector, to obtain a center of the target based on the point cloud data acquired by the circular scan and the diameter, and to measure a distance of the center of the target.