When the target has a small vertica

When the target has a small vertical angle, positioning the target point in the center of the field of view can reduce the effect of κ on the horizontal and vertical angles, the effect of β on the vertical angles, and the effect of α on the horizontal angles, but it cannot reduce the effect of β on the horizontal angles or that of α on the vertical angles. Therefore, during actual measurements, the coaxial camera in the IATS must be calibrated, the parameters affecting system errors, such as κ, α, and β, must be determined, and system mounting errors must be considered in the equations when calculating the corrections of the angle observations based on image measurements to obtain measurement results with high precision.