TARGET UNIT

A surveying system includes a target unit having a reflection target and an encoder pattern showing an angle of the target unit; a scanner configured to acquire three-dimensional point cloud data, measured coordinates of the target, and optically read the encoder pattern to acquire an encoder pattern read angle; and a leveling base configured to selectively allow either of the target unit and the scanner to be removably mounted. The scanner calculates a direction angle of the leveling base based on the encoder pattern read angle and the offset angle of the target unit, calculates coordinates of an installation point of the target unit based on the measured coordinates of the target and the direction angle of the target, and calculates a direction angle of the scanner based on the offset angle of the scanner and the direction angle of the leveling base on which the scanner is mounted.