Abstract: A one-dimensional calibration object consists of three or more collinear points with known relative positions.It is generally believed that a camera can be calibrated only when a 1D calibration object is in planar motion or rotates around a fixed point. In this paper, it is proved that when a multi-camera is observing a 1D object undergoing general rigid motions synchronously, the camera set can be linearly calibrated. A linear algorithm for the camera set calibration is proposed, and then the linear estimation is further rened using the maximum likelihood criteria. The simulated and real image experiments show that the proposed algorithm is valid and robust.