Survey system

A survey system comprising:

• a mobile body equipped with a scanner configured to scan a survey target by a distance measuring light;
• a position measuring device configured to measure a position of the scanner;
• and
• a posture detecting device configured to detect a posture of the scanner,
• wherein
• the posture detecting device includes an imaging unit configured to acquire image data by periodic photography, a 3-axis gyro sensor configured to detect 3-axis posture angles of the scanner, and an arithmetic control unit, and the arithmetic control unit is configured to calculate posture information of the scanner by summing photographing-time 3-axis posture angles of the scanner acquired in each photographing by image analysis of the image data, and 3-axis posture relative displacement angles of the scanner calculated by subtracting 3-axis preceding posture angles detected by the 3-axis gyro sensor at each photographing time by the imaging unit from 3-axis following posture angles detected by the 3-axis gyro sensor in an interval in which photographing is not performed in the interval by the imaging unit.