Abstract: A method and a system are disclosed for maintaining accuracy of a photogrammetry system comprising a stereo pair of cameras and characterized by calibration parameters determined at initialization, the system for tracking one of a touch probe and a 3D sensor, the method comprising in use, continuously detecting a presence of a reduced number of 3D target points comprising at least one pair of 3D target points selected in a group comprising at least two 3D target points; measuring image position data associated with the at least one pair of 3D target points of the reduced number of 3D target points; computing at least one updated calibration parameter using the measured image position data and corresponding reference distance data associated with the at least one pair of 3D target points of the reduced number of 3D target points; and updating at least one calibration parameter of the photogrammetry system.