AbstractImage-assisted total stations (IATSs) have extensive application prospects in astronomic surveys, deformation monitoring, precision engineering surveying, and topographic mapping. During image processing of data, the angle measured by the total station must be analyzed together with the image information, and therefore, camera system errors must be considered in addition to the systematic errors of the total station. Systematic errors of total stations can be eliminated or reduced by calibration. However, there is a lack of effective methods for the correction of the camera system errors. We analyzed the mounting error sources of the camera systems of IATS, constructed a model for the conversion between pixel coordinates and the angle measurements of the total station as well as an error correction model, and analyzed the effects of system mounting errors on the angle measurements. We also determined the effects of camera system mounting errors on the angle measurements using celestial objects. The results show that if both the horizontal and vertical components of the coaxiality error are assumed to be 2″ and the elevation angle is 50°, the errors of the horizontal and vertical angles can reach 3·0″ and 2·0″, respectively. These errors must be corrected for on-ground precision measurements of the astronomical longitude, latitude, and orientation, which require a precision of 0.1″.